Samsung U600 problems

Hello guys,

I don’t know if this is in the correct section or not but here goes:

In March, my dad was going on holiday to several countries in Asia (india and others), and because he has a pay-per-month phone which had no coverage in Asia, I let him borrow my pay-as-you go phone (a Samsung U600).

He inserted different simcards while he was there and it worked perfectly. But when he came back to the UK and I put my old T-Mobile sim card in, it keeps on saying ‘‘Limited Service’’ or ‘‘Searching’’ (I also tried other simcards). Since then, I cannot make any calls or receive them, it says ‘‘Emergency Only’’ but even when I call the emergency hotline it ends the call after 5 seconds (without a dial tone).

3 days ago, my phone encountered another problem. When I slide my phone up the screen turns off (instead of turning on), but if I slide it a little bit down (from the fully slided up position), it turns on again. So if I want to see my screen I have to hold it at halfway; this is very annoying. Also when I attempt to change the screen brightness, it decreases the brightness when I want to increase and vice-versa.

2 days ago, I could not play music loud anymore (with the built in speakers) but I could play the music through headphones. Yesterday, suddenly the speakers worked again but unfortunately today they stopped working.

Also, I have tried the code for full factory reset

What type of issue is this? Hardware? Firmware?

BTW: I have owned this phone since March 2008 and it had no problems until this year. (I feel the problems are connected)