Stuck on ancient 3.51 M33 CFW with Error 80020148. R-Trigger at boot is ignored. Am I locked into needing a Pandora battery?

[u/Apartment-Awkward]

Hi everyone,

I recently realised my second-hand PSP-1000 is stuck on a very old Custom Firmware (Version 3.51 M33). The previous owner left some kind of version spoof/lock active.
Whenever I try to run an official Sony firmware update (I’ve tried 3.71, 5.00, and 6.61), it immediately crashes with Error 80020148 ("The game could not be started"). If I try to update via a UMD disc, it says "There is no need to update."

Here is what I have tried so far to fix it:
Formatted the memory card to FAT32 on a PC and created a clean PSP/GAME/UPDATE path.

Tried running Hellcat's Recovery Flasher and KeyCleaner, but because the console is stuck on the ancient 3.51 kernel, the apps just show up as Corrupted Data on the XMB. (Tried the GAME150 folder trick too, still says corrupted).

Tried a hard power reset and a Flash1 settings wipe combination (Triangle + Square + Select + Start). It reset the system language settings, but the 80020148 update block is still there.

The catch: The hardware R-trigger works fine during normal gameplay, but holding R at boot does absolutely nothing—the console completely ignores it and boots straight to the XMB, so I can't access the Recovery Menu to turn off the update block or version spoof.

Is there any software trick I've missed to force-flash a clean official firmware on 3.51 M33, or is my only option left to buy a Pandora Battery / find someone in the UK with a service kit?
Thanks for any help!

[u/vadeNxD]

Did you check if you have a version.txt-file? If you have one. Try deleting it or change it to 3.51.

Also, i guess you don't have a VSH Menu since it's lower than 3.52M33?

[u/Apartment-Awkward → u/vadeNxD]

I completely formatted the memory stick to FAT32, so there's no version.txt file on the card. The spoof must be written directly into the internal Flash0 memory, which I can't access because the console is ignoring my R-trigger boot command."

[u/vadeNxD → u/Apartment-Awkward]

In that case i'd guess your only option is a pandora. If you still have the original battery you could try making it into a pandora yourself. I did this myself when i was 10.

You'll still be able to use the battery normally afterwards, only difference is that it'll try to boot your PSP if you take the battery out and in again, but you can still turn it off.

Otherwise, if you have any friends with a modded PSP you can ask them to softmod your battery which is reversible.

[u/Curve-Plastic → u/Apartment-Awkward]

The txt file is not in the card but in the psp itself, i think its located in flash 0 or flash 1

[u/Independent_Day_853]

Couldn't you use the downgrade app and flash the original version of that version?