If you have more than one memory module then try one module at a time. It may be that one of the RAM modules is defective. If that does not help then try replacing the CMOS battery with a brand new battery. Leave the old battery out of the system for 15 minutes before installing the new one. If that does not help then possibly the RAM modules or the MB has problems. Pull all the RAM out and try booting just to confirm that the system detects no RAM and you should hear beeping to confirm it. 

Agree w JOcean.  The hard shutdown may have caused cmos setting logic confusion.  Try d/c power cord and press power button for at least 30 sec.  Replace cmos battery as already advised.  I would also try clear cmos settings by motherboard RTCRST jumper.

If by chance those troubleshooting steps don't work, replace the RAM.  A-Tech is one good way to save money on an older/somewhat older machine and it comes with a lifetime warranty.  I've used it for years.

Sounds like you were having trouble with it before the forced shutdown.