From the picture you can easily tell that the cpu was constantly busy doing something. Best tools to diagnose what's going on under the hood is top/htop and powertop.

In perfect conditions using powertop you should see that most of the time (ie: 95%) cpu is doing "nothing" in C4. If this number is lower this app should tell what process is most often waking up cpu.

Also I'd check if all unneeded radio's are off (gps, bluetooth, wifi etc..), and maybe reboot the device. Last time I was using GPS and ovi-maps I noticed that after ovi-maps switched on GPS it did not shut it down on exit. Also after closing maps were still running in the background... Reboot helped.

For wall charger issue as cjp said - first I'd check if charger is not broken. Then try to reflash to 1.3, then to 1.2 and finally ask for nokia service.