USB PORT PROBLEM on SGS2 UK orange

HI boys

i have bought one phone from second hand for good price

phone look like new without any problems working good

but i mean that there is USB port problem, charging OK , but when i plug the charger in first time phone was totally without enegry ( it shows yellow triangle near the battery icon ( but only for few minutes)

in this case when i connect phone to PC there is only charging and nothing more
already trying USB debug mode on/off , download mode when i connect windows just says unsupported device
iam trying 3 SGS2 , 3 PC and also 4 USB Cables

usb JIG working good it go to download mode and earse all data counter without problem

is there any good specialst who can help me ? i want to order USB flex cable part and chanage, it is enought?

many thanks

already done , but without luck

iam not stupid, i had 3 sgs2 and this is first problem like this,

in service they told me that i have to pay for diagnostic first,( so no good )

iam without waranty, but if i chanage usb port flex cable iam not shure if this one can fix,

as i didnt know about history of phone ( maybe was water damage ?)

but all working like charm, phone looks like new( except USB connection)

so why the USB JIG working ? which pins is connected via JIG?
Also charging is good , some circle can be broken?

i will try to risk order one flex usb connector for sgs2

http://www.parts4ipods.com/epages/es115703.sf/en_GB/?

it cost just 7 GBP free psotage to worldwide

i hope that i will not more destroyed my phone , dissassembly looks no good ...

yes iam technican engeneer , but iam afraid about that , if i broke some more thing in, than can be more expensive repair

and iam not sure that is this flex cable problem

but better than soldering someting on motherboard