If you have stuffed it up and your probably not going to use it (as it is quite easy to program it via ponyprog) cut the power trace and don't use it.
If its you own then be free to do what you want
Other than that get the iron tip really clean , get some flux or 'bakers fluid' and heat the tip up and dip it in then clean, then tin the tip with solder and wipe the excess solder off.
Then use braid or a solder pump. Keep a steady hand and don't rush it
You could also cut the bridge with a banned (?) but try to get as much of with braid or a pump.