The area in question was the ground strip adjacent to the battery... everywhere else should be fine as is - you only want to work on affected/suspect areas...if you've left too much solder on the other areas, remove it with copper braid solder wick (it should have been applied as a smooth thin application, using the solder iron along the strip),
All the suggestions I've seen are good sound ones, but it only takes one minor fault to glitch the system...
BTW, hopefully not chasing our tails, but there should be a ground wire from the back panel to the metal sheet under the boards - that lug should be secure, not loose, to ensure a good grounding of that noise shield