I suspect the (now approx. 10 year old) RTC/NVRAM battery (coin-cell) has died, what is the current voltage of the existing battery and what happens if you replace it with a new one? Unfortunately according to the 700M Service Manual
that unit uses a semi-proprietary battery with an integral pigtail vs. a bare one (e.g. CR2032) you could get anywhere for a couple dollars.
If replacing the NVRAM battery doesn't help, then what happens if the AC is connected but the main battery is removed? Is the main battery charging properly? What happens when you power it up without the AC power connected? Try entering the BIOS Setup and re-saving the settings. Let me know what you find, Scott.