There is no chance to update from 3.48 to 3.51 with sd card plugged in !!!, i found out few moments ago. It always said error after installation, *#7370# did not help at all. After i unplug sd it went smoothly.
SW contains a lot of BUGs, just try to set SIM lock off(starting without PIN code request) for both SIMS, if you turn off the phone it will turn on by itself after 10-15 seconds !!! Yes there is workaround, set fly mode and then turn off :) it won´t turn on in that case.
Anyway great phone, battery last for 2 weeks without charging :)