Bah... flashing the eMMC as well didn't help too... I didn't restore any setting this time, just flashed the firmware and eMMC and installed BatteryGraph to monitor the battery performance, but still it drains fast.

I thought this might be related to BatteryGraph so I uninstalled it, and installed BatteryEye instead - but still it drains fast.
The problem must be related to my batteries (even though its kinda odd both of my batteries are affected by this at the same time), or in my phone itself (which is more likely, though I have no idea what can cause this)...