Help, Strange VPCZ1 Turn On Problem

My laptop is VPCZ115GG, the model for Asia with HDD. I did the BIOS hack a long time ago with no problem. I own two battery, one original battery and one OEM Battery. There was no problem. I can turn off my laptop, change the battery to OEM battery with no problem. I can also turn off the laptop, change the battery to original battery with no problem. (All was done with the laptop not plugged to power supply). Then the problem starts after:

First I opened the laptop to clean the dust off. After I clean the dust, i put OEM battery on, then turn on my computer. Everything was normal except that my bios clock was reset. After that I plugged my power supply.

After that I delete windows system reserved partition, merge the deleted partition with Windows install partition, then did a start up repair with windows install disc. My laptop can now boot to windows 7 normally, but I noticed 1 problem, my fingerprint software cannot be used. I don't use fingerprint, but windows 7 notify me about the problem. I uninstalled protector suite then install it again, but the problem doesn't go away.

Next, I installed Windows 8 Release Preview in another partition. Played with it for a while, then back to windows 7. Last night, I leave my laptop on with the OEM battery and the power supply unplugged. I thought that when the battery low, windows will go to sleep mode. When I checked in the morning, my battery drained out and I have to plug my laptop to power supply to turn it on. Then, I think I'll charge my original battery too (my original battery was not empty. I still has maybe about 30-40% in it).

I pulled my power supply. Take out the OEM Battery, then put my original battery in. My laptop won't turn on. Then I try pluggin my laptop to the power supply, and the laptop started by itself, no need to push the power button. The clock was reset. Windows 7 start with no problem. I can restart with no problem. I can shut down the laptop, pull the power supply out, and turn on again with only the battery.

However, if I pull the original battery out, and pull the power supply, then put the original battery back in, I can not turn on my laptop. I have to plug my laptop to power supply, and then the laptop will turn on without having to push the power button. the clock was reset.

If I pull the battery out, then pull the power supply out, then put the OEM battery in, I can turn on the laptop without needing to plug the laptop to power supply. just put the OEM battery in, open the lid, then push the power button, then the laptop will turn on. the clock was reset.

Tried reflashing to original unhacked BIOS but still doesn't solve my problem.
Can someone please help me? What action I did that create that problem and how to fix the problem? Thank you very much.

 

look when you opened you laptop you probably accidentaly unplug cmos batt

plug back and all will be fine

 

Thank you sooo veerryy much urgiv. I just checked my laptop and yes, i forgot to plug my cmos battery. Now all problem is solved.
However I'm still curious why it can start with oem battery and not with original battery. Well, the important thing is, my laptop is back to normal. So, one more time, thanks urgiv.