imac g3 mac os x 10.2 upgrade disk error boot
iMac, Mac OS 9.2.x, imac g3
iMac, Mac OS 9.2.x, imac g3
You are lucky that's all that happened. Your imac probably needs a firmware update applied while booted into 9:
https://discussions.apple.com/docs/DOC-2125
I would also have a technician make sure the PRAM battery is under 4 years old.
imac g3 mac os x 10.2 upgrade disk error boot