I can tell you that 2 of the dodgy ones I had where model:HLT-USB, now I found a way to fix them after months of them sitting in my box of knackered bits all due to a friend screaming at me his xbox went tits up and we reflowed it in the oven and that got me thinking what if the original flow wasn`t quite hot enough or the boards weren`t in long enough or they cooled too quickly and due to that line of thinking, below is what followed. ;)

you need to take the casing off then gentle pull 510 connector wires out straight same with usb cable end, as you dont want to melt them, now take a cooks blow torch and holding charger in other hand by usb cord move blow torch back and forth across componet side medium paced so as to be constanly moving. There needs to be about 3-4 inches between blow torch and circuit board, do about 8-12 times back and forth let it cool and now hopefully its reflowed and should be working correctly. :)

Its worth a try if you get one thats not behaving as you think it should, needs shorting or is stuck on red light, its amazing what problems a dodgy bit of flow/solder can cause.