OnionOS Setup Guide for the Miyoo Mini Plus

The Miyoo Mini Plus runs stock firmware out of the box. Almost nobody keeps it. OnionOS has become the expected starting point for this device — not a mod you install when you’re feeling adventurous, but something you do the same afternoon the package arrives. If you’ve landed here after unboxing your Mini Plus and wondering why the default launcher feels so bare, this guide will walk you through a clean OnionOS install from scratch.

The install takes roughly 20 minutes, requires no soldering, no ADB commands, and no disassembly. The risk level is low: if something goes wrong, you reflash the stock firmware and start over. Nothing touches the device’s internal storage.

What you’ll need

• A Miyoo Mini Plus (OnionOS supports only the Miyoo Mini family — it will not run on Anbernic, Retroid, or any other device)
• A microSD card — community reports suggest up to 512 GB works reliably; a Class 10 / U1 card or faster is recommended
• A second microSD slot or USB card reader on your PC
• balenaEtcher (or manual file extraction to SD card root — both methods work)
• The OnionOS release archive from GitHub
• 20 minutes, no special skills required
• Risk level: low — fully reversible by reflashing stock firmware

Before you start

Back up anything on your existing microSD card. The flashing process will overwrite the card’s contents. If you’ve already loaded ROMs or save files onto the stock card, copy them to your PC first.

OnionOS does not touch the Mini Plus’s internal hardware in any way. The recovery path is straightforward: if you want to go back to stock, flash the stock Miyoo firmware image to the card the same way you installed OnionOS. Keep that stock image downloaded somewhere just in case.

Step 1: Download the firmware

Go to the official OnionOS releases page:

https://github.com/OnionUI/Onion/releases

Download the latest stable release — 4.3 is the current stable branch, with 4.4 in beta as of early 2026. The release assets are hosted directly on GitHub. Verify the download against the SHA256 checksum listed on the release page before flashing; GitHub release signatures are available there.

Don’t download from third-party mirrors or YouTube video links. The GitHub releases page is the only authoritative source.

Step 2: Prepare the SD card

OnionOS can be installed by extracting the archive contents directly to the root of a FAT32-formatted microSD card. For most users, balenaEtcher handles the full process if an image file is provided; otherwise, manual extraction to card root is the supported method — both are listed as valid tools in the official documentation.

If you’re formatting manually, use FAT32 for cards up to 32 GB. For larger cards (64 GB and above), exFAT is typical — but check the current OnionOS documentation for the recommended filesystem, as this can change between releases.

Step 3: Flash the image

1. Open balenaEtcher and select the OnionOS release file as the source.
2. Select your microSD card as the target. Double-check the drive letter — you do not want to overwrite the wrong disk.
3. Click Flash and wait for the write and verification passes to complete.

If you’re using the manual extraction method instead, unzip the OnionOS archive and copy all contents directly to the root of a freshly formatted card. Don’t place them inside a subfolder.

Eject the card properly from your OS before removing it — don’t just pull it.

Step 4: First boot

Insert the flashed card into the Mini Plus and power on. The first boot takes longer than subsequent boots — OnionOS performs initial setup tasks including building its package list and preparing the frontend. Don’t panic if the screen shows a logo for 30–60 seconds.

You’ll be dropped into an Apps > Package Manager flow that lets you select which emulator cores and system packages to install. This is where you choose what platforms you actually want — you don’t have to install every core at once.

Common first-boot issues:

• Black screen after logo: The card write may have been incomplete. Re-flash and ensure balenaEtcher reported a successful verification pass.
• Launcher shows no systems: You need to run Package Manager and install at least one emulator core, then place ROMs in the correct folders.
• WiFi not connecting: The Mini Plus uses 2.4 GHz only — a 5 GHz-only network will not appear in the list.

Step 5: Add your games

OnionOS uses a straightforward directory structure on the SD card. Each system gets its own folder under /Roms/. The folder names map to emulator systems — the exact names are documented in the OnionOS wiki on GitHub.

Typical layout (examples):

/Roms/GBA/      ← Game Boy Advance
/Roms/SFC/      ← Super Nintendo
/Roms/PS/       ← PlayStation 1
/Roms/NDS/      ← Nintendo DS (added in v4.3)
/BIOS/          ← BIOS files

BIOS files go in the /BIOS/ folder at the card root. PS1 in particular requires BIOS files to function — the exact filenames needed are listed in the OnionOS documentation. Check the GitHub wiki rather than relying on generic RetroArch BIOS lists, since naming expectations can differ.

The Mini Plus handles NES, SNES, GBA, and PS1 all at full speed under OnionOS. Nintendo DS via DraStic (added in v4.3) works for a wide range of titles, though performance varies on heavier 3D games given the hardware’s 128 MB RAM. N64 is not practical on this hardware — don’t bother including those ROMs.

Common issues and fixes

Symptom	Likely cause	Fix
RetroAchievements not working	Not logged in	Open Apps > RetroAchievements and enter credentials
DS games not showing	Missing core or wrong ROM folder	Reinstall DraStic via Package Manager; confirm ROMs are in /Roms/NDS/
WiFi drops repeatedly	2.4 GHz congestion or WPA3 network	Switch router to WPA2 or move to less-congested 2.4 GHz channel
Games not appearing after adding ROMs	Cache not refreshed	Hold Select on the system in the launcher to refresh the game list
Short battery life	Screen brightness too high	OnionOS includes a battery optimization mode; reduce brightness in Settings

Performance tips

OnionOS ships with sane defaults for the Mini Plus, and for the platforms this hardware is built for — NES, SNES, GBA, PS1 — there’s genuinely little to tune. A few things worth doing regardless:

• Enable the blue light filter (added in v4.3) if you play in dim environments. It’s in Apps and reduces eye strain noticeably on extended sessions.
• Set up the Activity Tracker — it logs play time per game, which is a small feature but one no other CFW on this device offers.
• Use the sleep mode rather than powering off between sessions. OnionOS’s sleep implementation is rated well by the community; it preserves state reliably and saves the 3000 mAh battery for actual play.
• Screen recording is available as of v4.3 if you want to capture footage without an external capture card.
• For DS games specifically, DraStic has its own settings menu accessible mid-game. If a specific title is running poorly, check whether the DS rendering mode or frame skip settings in DraStic can help — this is more effective than adjusting global RetroArch settings.

OnionOS also includes VNC remote display and control, which sounds niche but is genuinely useful during initial setup: you can control the device from your PC to configure emulator settings without squinting at the 3.5-inch screen. Launch it from Apps > VNC on the device, then connect with any VNC client on the same WiFi network.

Netplay is supported for systems that have compatible cores — useful if you want to run a SNES or GBA session with someone remotely, though the 2.4 GHz-only WiFi on the Mini Plus means connection quality depends heavily on your router placement.