Reset the time and date n the BIOS .. it should then boot
If the BIOS clock goes out at every
boot, you need a new BIOS battery .. This is NOT the same battery as the large one for the laptop, it's a tiny battery inside the laptop. Similar (depending on model) to the one pictured top right here:http://www.ifixit.com/Guide/Repairing+IBM+ThinkPad+T41+BIOS+Battery/2916/1
Usually (but not always) a "Coin Cell" CR2032 battery that either clips into a holder on the motherboard .. or as with the thinkpad T41 (above link), a CR2032 that has wires and a plug soldered to it and is then shrink wrapped.
Fitting can be anything from a doddle (battery accessible through a trap door), to a nightmare (semi or total stripdown of the laptop).
That said .. some older PC's had rechargeable BIOS batteries .. so try just giving it time (turned on) to charge, then see if the BIOS clock has retained its settings for a useful amount of time.