How to Install muOS on the Anbernic RG35XX Plus

The RG35XX Plus runs stock Anbernic Linux out of the box, and while that firmware is functional enough, it gets out of the way quickly once you’ve experienced a proper custom OS. muOS (MustardOS) is where most RG35XX Plus owners land: it’s actively developed, explicitly built for Anbernic hardware, and strikes a balance between a clean modern UI and real emulation depth that stock firmware simply doesn’t offer.

This guide is written for first-time muOS installers on the RG35XX Plus specifically. You don’t need soldering skills, you don’t need to open the device, and the whole process is reversible if something goes sideways. Expect to spend about 30 minutes from download to your first game loading.

What you’ll need

Two microSD cards (strongly recommended — one for the muOS OS image, one for your ROMs and BIOS files). The RG35XX Plus has dual microSD slots, which makes this setup clean.
Cards rated at Class 10 / UHS-I or faster for reliable performance
balenaEtcher or Rufus for flashing the image
A PC or Mac with a microSD reader
~30 minutes from start to first boot
Risk level: low — the process is reversible by reflashing stock firmware

Before you start

Back up anything on your existing microSD cards before you touch them. The 64 GB card that ships with the RG35XX Plus typically comes pre-loaded with ROMs from Anbernic — those will be wiped when you flash muOS to that card.

If you want to keep the stock firmware accessible, grab a spare card (any old 8 GB card works) and image the stock OS to it first using Rufus or dd. That way you can swap back without re-downloading anything from Anbernic.

Step 1: Download the firmware

Go to the official muOS releases page:

https://github.com/MustardOS/frontend/releases

Find the latest stable release. On the RG35XX Plus, you want the BANANA build — that’s the device build codename shared between the RG35XX Plus and the RG35XX H. Downloading the wrong build for a different device won’t work correctly, so double-check the filename before proceeding.

Each release includes SHA256 hashes in the release notes. Verify your download before flashing:

On Windows: certutil -hashfile muOS-BANANA-x.x.x.img.gz SHA256
On macOS/Linux: shasum -a 256 muOS-BANANA-x.x.x.img.gz

Compare the output against the hash posted in the release notes. If they don’t match, re-download — a corrupted flash image will cause boot failures that are annoying to diagnose.

Step 2: Prepare the SD card

Insert your OS microSD card (the one that will hold muOS) into your card reader. You don’t need to format it manually — balenaEtcher writes the image and creates the correct partition layout automatically.

If you’re using Rufus on Windows, select DD image mode when prompted, not ISO mode. ISO mode will not produce a bootable result.

Your ROM card (the second card, which goes in the lower slot) should be formatted as exFAT. Most cards come formatted this way already. If yours isn’t, format it in exFAT before the first boot so muOS can write its folder structure to it automatically.

Step 3: Flash the image

Open balenaEtcher (or Rufus).
Select the muOS BANANA .img.gz file you downloaded. Most tools can flash directly from the compressed file — no need to extract it first.
Select your OS microSD card as the target. Be careful here: selecting the wrong drive wipes whatever is on it.
Click Flash and wait. On a modern USB 3.0 reader with a UHS-I card, this takes 5–10 minutes.
When flashing completes, eject the card properly. Don’t yank it — some tools write verification data after the main flash.

Insert the flashed card into the upper microSD slot on the RG35XX Plus (TF1, nearest the top of the device). Insert your ROM card into the lower slot (TF2) if you’re using the two-card setup.

Step 4: First boot

Power on the device. The first boot takes longer than normal — muOS is expanding the filesystem and setting up its directory structure. Give it a full minute before assuming something is wrong.

When the setup screen appears, you’ll be asked to:

Select your device type — choose RG35XX Plus from the list.
Set the time and date — muOS doesn’t pull time from the internet on first boot, so enter this manually. It affects RetroAchievements timestamps and save file metadata.

After setup, muOS drops you into its main menu. The UI is clean and navigates with what you’d expect: D-pad to browse, A to confirm, B to go back. If the screen is on and you’re looking at the muOS main menu, the flash worked correctly.

Step 5: Add your games

On first boot, muOS writes a ROM folder structure to the second microSD card (lower slot). Power off the device, remove the ROM card, and connect it to your PC.

You’ll find directories organized by system. Drop your ROMs into the appropriate folders:

Game Boy Advance → ROMS/GBA/
SNES → ROMS/SNES/
PS1 → ROMS/PS1/
N64 → ROMS/N64/

(Folder names may vary slightly depending on the muOS version — check the actual directory names on your card rather than assuming.)

BIOS files go in a BIOS/ folder on the ROM card. PS1 in particular needs BIOS files to run. Place the correct BIOS files here before expecting PS1 games to launch. muOS’s documentation on the project homepage lists which BIOS filenames and checksums it expects per system.

Once you return the card to the device and power on, muOS will scan and populate your library. With a large ROM set, the initial scrape can take a few minutes.

Common issues and fixes

Device won’t boot after flashing Most likely cause: wrong build. Confirm you downloaded the BANANA build, not BEANS (that’s for the RG35XX SP) or one of the RG40xx builds. Re-flash with the correct image file.

Black screen on first boot, then nothing Try a different microSD card. Some off-brand cards have timing issues with the H700 SoC that cause silent boot failures. Name-brand UHS-I cards (Samsung, SanDisk, Lexar) are more reliable here.

ROMs not appearing in the library Check that your ROM card is formatted exFAT and that ROMs are in the correct subdirectories. muOS will not scan the root of the card — files need to be inside the system-specific folders.

RetroAchievements not connecting muOS supports RetroAchievements, but you need to enter your credentials in the muOS settings menu after connecting to Wi-Fi. The RG35XX Plus connects to both 2.4 GHz and 5 GHz networks (802.11 a/b/g/n/ac), so either band works.

Wrong time/date after setup Go back into muOS settings and set it manually. There’s no NTP sync on first boot by default.

Performance tips

The RG35XX Plus with muOS handles GBA, SNES, and PS1 at full speed without any tuning required. N64 and Dreamcast are more hit-or-miss depending on the game — these are playable for many titles on the H700 platform, but you’ll find exceptions in both libraries.

muOS includes overclocking support. If you hit a game that runs slightly under full speed, a modest CPU frequency bump often resolves it. That said, overclocking increases heat output and reduces battery life from the 3,300 mAh cell, so treat it as a per-game tool rather than a global setting.

Keep your ROM card under 512 GB per slot — that’s the manufacturer-specified expansion limit. Beyond that, card compatibility with the H700 platform becomes unpredictable in community experience.

If you’re coming from stock firmware, the stereo front-facing speakers on the RG35XX Plus will sound noticeably better once muOS is letting you set per-system audio settings. The hardware was always capable of it; stock firmware just doesn’t expose the same level of control.