G4 Boot Issues

I have a G4 PowerMac that will not boot up. I power up the computer and it stalls on a grey screen with text prompting me to type <<boot>> if you wish to continue...or something like that. Does anyone have any advice on how I might troubleshoot this? The computer was working fine for a few days before this occured. It has been unused and sitting is storage for a while. Thank you for your time.

I believe that is in single user mode, but I can't be certain of that because it is not my computer. Thank you for your time. Any input is appreciated.