My beloved N900 suffered this issue and Android phones cannot satisfy me. Couldn't get it repaired from any service centre. Fixes suggested dint work. Anyone can fix mine,? I'm ready to ship it internationally to anyone who can fix it. Thanks.

Some are not fixable, for example if it is related to the pcb or when the chip is broken inside. If it is only resoldering of the chip I think you could find a company also in India. In principle you only need a blast pipe for this chip size hot nitrogen and a cooling for the other side of the pcb.

When a proper resoldering was already tried, then the next thing would be to replace the chip. If this is also not working to find the real fault and solve it will cost to much.

BTW what have you tried already? It could be that wrong repair could put more damage to the device.

Was the fault of the modem occasionally or once and then for ever?

the only fix I found after surfing around for it was to use it as a music player and find another N900 and another and another..
Sorry to hamster away all those N900 while they were cheap

Defects I have encountered so far on various, not same N900:

-GPS not functioning
-All telephone functions disabled turning the phone into a surfing tablet / music player.
-Display messed up (booting but rubbish on screen)

GPS alone works on every n900 and up to this time I never have met n900 with physically broken GPS chip. A-GPS is another story but it doesnt need much from GPS reciver. It feeds localization with information from cell towers to get faster FIX. GPS alone will get FIX eventually but it can take time. A-GPS on the other hand is easy to fix and there is also thread about this.

Telephony functions are disabled because of problem with modem on hardware side. I don't know what can cause this but what I know is that the problem is fixable. All you need to do is to apply few small springs with glue to modem chip to get more pressure on it. I don't know how it works but I did that two times. One unit with this fix had many different problems and finally gave up, but second is still working to this day.

Display problems are rare. The screen on n900 is deep in case and most of the close contacts with the floor doesnt even reach it. It is still killable but needs very hard kick. Used screen for n900 costs around 10 dollars and are easy to replace.

But there are many units still available on the aftermarket and so many times fixing your device on some service station will costs you more than used unit in good shape.

N900 main problem is with the USB port beeing too weak and breaking loose. But for this is also an fix and preventing-fix