SGS2 mobile connectivity/GPS intermittent problems after DIY repair Looks like my SGS2 started to have mobile connectivity/GPS problems, possibly as a result of DIY repair (I manually replaced LCD+digitizer after an LCD damage):


GSM signal level frequently drops to nearly zero
mobile data speed drops to (nearly) zero
GPS works only rarely; can't fix most of the time


How can I debug the problem? Which connectors etc to check most carefully which can directly affect the problem? What else to try?

Official firmware auto-updated to 4.1.2. GT-I9100. GSM, non-locked, international version.
Ive also disassembled completely my S2 a few times also because of its LCD (it was black sometimes I could see a few pixel flashing in random colors or if i was lucky the whole screen was covered in horizontal blue stripes after repeatedly being covered with a tint of a different colour)

You need to make sure the antenna is properly inserted make sure it is as straight and tucked in as possible (Push it under with something (be careful not to scratch the PCB) and maybe look at some picture how it should be.)

Look for any damages to anything.

Also it might be a good idea to clean the contact (I heard isopropyl alcohol is good and the purer it is the better but I'm not sure if it is good for phones)

Consider flashing a rom with the latest android (now is 4.4.2) and a better kernel should help.Don't bother about warranty you can always go back to stock even if the LCD dies again.