Help. How to recover with no reset button?

Help. How do I recover from a fault during boot up when mouse and keyboard don’t work and there is no reset button? It is an Rpi3B+ with a wired Rpi keyboard and mouse. I can take out the SD card and put it into a USB adaptor but my back up versions of RISC OS don’t seem to be able to read it. I think I know what caused the crash, but that does not help much. Other OSs presumably cannot read the filecore-formatted SD card.

A quick thought: You are right-clicking on the drive when trying to read the card? A left-click will only display the bootloader partition.

The special card formatting makes it look like FileCore to RISC OS, but FAT to other OS’s. If other machines can’t read either the FileCore or FAT information, it’s probably corrupt.

@Stuart. Alas I cannot even get an icon to click, whatever the mouse button.

I have an Ubuntu CD which I use in my Windows PC so that I can examine badly performing SD cards. Using the Disk Utilities, you should see two overlapping partitions, one filecore (which Linux can see as a partition but not see the files inside) and one FAT (which Linux can see and display the files).

The RPi3B+ has a RUN header on J2 – short pin 2 of J2 to ground to do a reset.

Try the SD card in another Raspberry Pi.

Just a thought. If you have a spare SD card and USB stick, could you set that up to boot RISC OS from USB, then replace SD card with the one you’re having issues with?
No idea if that will work, but I have booted from USB before.

I do not think booting from USB is an option on a raspberry pi for version numbers less than 4.
I have ordered a batch of 4GB micro-SD cards for flashing RISC OS onto. My strategy is to put as little as possible on the SD card, and to have bigger storage attached. I fear that the old SD card was damaged when I switched off without being able to give the system notice that it was to close down.

Not only has the raspberry pi no reset button, the raspberry pi keyboard has no BREAK key. Yet all the ROOL documentation mentions is this nonexistent key, so I think it needs emending. That is the weakness of having all your input via USB. Once that crashes, you are stuck.

I had to use my old RPi2 to update the RPi4 card when I’d stripped the filetypes off the new updates :(

Yet all the ROOL documentation mentions is this nonexistent key

I have made alterations to 6 wiki pages – for example Beginners FAQ:Troubleshooting – to indicate what to do if your keyboard does not have a Break key. If you feel there are other wiki pages that need adjustment, please let me know.

I have made alterations to 6 wiki pages

That is excellent. Very useful.