Powerbook G3 (Pismo) stuck at gray scree

[mythago]

Hello, I have a Powerbook G3 400mhz (Firewire/Pismo) running Tiger (OSX 10.4.9) which I bought used, with a dead PRAM battery. I replaced the battery and upgraded the 'lower' RAM stick to bring the computer to 1G of memory. Now I cannot get it to boot past the Apple logo and spinning circle - it goes straight into gray screen. I have tried all of the suggestions at Apple Support including resetting NVRAM and PRAM, using the reset button on the back, unplugging the PRAM battery, etc. I put back the old RAM chip. It will not boot up from the install CD (although it will spin up). I have tried Open Firmware as well. Help!

[oldmanmac]

Did it boot before you did your upgrades?If it did,recheck your work,make sure all connections are made and tight,especially the hard drive.Do you have an external drive that you can boot from? Try that next.If you do not have one,connect the Pismo to another Mac with a firewire cable and try to start it in target disk mode.If the other mac sees the Pismo drive then you can run diagnostics on it. if it can't be seen,possible failed drive.
As for your optical drive,try cleaning the lens carefully.Once again if it still won't come to life,bad drive,bad connections,not uncommon at all!
Hope this will help.