[Google Pixel 4a Questions & Answers] mayday175:
I recently purchased a used Pixel 4a, and I now understand why the seller was offering such good price for it and why he refused to respond to me now I have it. This phone has ArcanseOS 10 installed, which has only 3 apps installed... Setting, Clock and Calculator. There is no Play Store app, no Phone app, nothing.

The only useful reference to ArcaneOS I can find in the Googleverse is this one... https://translate.google.com.au/tra...rueck-flashen.973774.html&prev=search&pto=aue where the OP describes his troubles with a Pixel 3. Through the rough translation, I see similar issues... can't enable developer mode, can't unlock bootloader, can't sideload apps.

Some random observations about this phone/OS...

- The phone is in good condition. I used the supplied pin code to unlock it and did a factory reset. Have done basic config with my Google Account, etc.

- In Settings > About Phone - the build number is not shown. I cannot tap on the build number 7 times to enable Developer Mode. I have tried tapping everything in About Phone 7+ times, but I have not been able to enable Developer Mode.

- When the phone powers on, the first thing shown is a message like "Your device is loading a differennt operating system".

- The installed OS is ArcaneOS 10. The system updater says that ArcaneOS 11 is available for download (but I don't want to do that in case it makes this thing even harder to fix).

- I tried sideloading open_gapps and a random developer shortcut app I found, but I can't seem to get them to load.

I'm no expert at this, so I've tried various commands that I found and got some of these results...

(note: some details, esp path names, have been edit for brevity)

>adb devices
List of devices attached
09241JEC228869 sideload

>adb shell
error: closed

>adb sideload open_gapps-arm64-10.0-stock-20210518.zip
adb: sideload connection failed: no devices/emulators found
adb: trying pre-KitKat sideload method...
adb: pre-KitKat sideload connection failed: no devices/emulators found

>adb sideload "by4a.setedit22_2018.10.31-18_minAPI11(arm64-v8a,armeabi-v7a,x86,x86_64)(nodpi)_apkmirror.com.apk"
serving: 'by4a.setedit22_2018.10.31-18_minAPI11(arm64-v8a,armeabi-v7a,x86,x86_64)(nodpi)_apkmirror.com.apk' (~47%) adb: failed to read command: No error

>adb shell settings put global development_settings_enabled 1
error: closed

>adb root
adb: unable to connect for root: closed

>adb shell
error: closed

>fastboot --version
fastboot version 31.0.2-7242960

>fastboot devices
09241JEC228869 fastboot

>fastboot flash bootloader sunfish-rq2a.210505.002\bootloader-sunfish-s5-0.3-7062598.img
Sending 'bootloader' (8357 KB) FAILED (remote: 'Download is not allowed on locked devices')
fastboot: error: Command failed

>fastboot flashing unlock
FAILED (remote: 'Unrecognized command flashing unlock')
fastboot: error: Command failed

Any suggestions on how to unlock this device? Then I can flash it and restore it back to stock.

Thanks

PS. Please do not say "tap build number 7 times to enable Developer Mode/options". If you believe this is the solution, please re-read this post, and the linked/German post, then describe a different way of doing that task that doesn't rely on the build number being visible.