My local portmap server went down, and I tryed to fix it with my Z. First strange thing I noticed - touchscreen did not work (tapping switches opened windows (fvwm)). I managed to get WLAN up and restart my portmapper. But I wanted to fix ts bugs. I removed /etc/pointercal file and restarted X. Calibration did not succeed, so I restarted Z. It did not even turn on. After plugging in AC adaptor, power led started blinking. D+M (diags menu) shows:
BAT0_V: 9.8
BAT0_T: 3.2
BACKUP: 3.2
Value of 9.8 seems to be really strange.
System still boots, if you press D+B (recovery flash partition), then reboot it by entering runlevel 6.

How to fix it?

Add: Real voltage at battery is 3.62V, so my battery is OK. IMHO there is something wrong with power curcuits.