Updated to 5.28 but lost file system

I have a Pi 1 which I tried up update to RISC OS 5.28 today.
Originally it was set up using NOOBS with Raspbian, RISC OS etc on the boot menu.
After the update it boots to desktop and then shows the error “Machine startup not completed. Disc not understood – has it been formatted”.
Now, if I use the same SD card and boot to Raspbian, I can see the RISC OS Loader files OK.

Can I get the RISC OS file system back?
How can I get this SD card to boot to a working system again?

How did you update it?

In RISC OS, copied the new OS files to inside the Loader DOS file.
It seems that the OS no longer knows where the ADFS partition is.

Whew, I got it back. Looks like either I overwrote one of the config files inside Loader or the PSU is not providing enough Amps. Thankfully I had the old Loader files on a memory stick.

Yes, I copied in RISCOS.IMG and the firmware files into the Loader file/partition. This is how I’ve updated it in the past by opening up Loader and copying in the new files. I know not to move or alter the Loader partition file itself.

I’ll try the upgrade on another SD card so I don’t corrupt my working one again. I’m not yet convinced the 5.28 files and firmware are compatible with Pi 1.

OK Good to know. Did you also update Loader with BOOTCODE/BIN, FIXUP/DAT and START/ELF in BCM2835.5.28.zip or just copy in the RISCOS.IMG file?