Yeah sounds like the power transistor will have failed to me.. Although it can be many problems.
It is small fine solder work, and its VERY easy to go wrong trying to remove the original one and ruin tracks for fitting the new one.
If you woud happen to be in the UK, or willing to ship into the UK i have a professional repair and upgrade service that could fit you the new part for a very low cost price.
If you wish to send your board in for professional repair then do PM me as all work is guranteed and is under our no fix - no fee basis.
Good luck with fixing your board also if you wish to go down that road