Got the same error as you on my new APM2.5.
Did try latest software og PM = no good (Upload succeeded, but verify failed: exp76 got 21 at 2)
Did try in CLI mode.... got this " NNNNNNNNNNNNNfN:$H@VxxxmaB;89///5Q! @ *@`5@E
"3 989000Z(@`st:…"
"Hi Guys
After installing APM version of the Aruino IDE 1.0.3 and uploadet the 3.06 code i'm having serious problems.
It's completely dead. Only the yellow LED is on.
And my APM 2.5 is now sending me garbage back when i connect it to MP i CLI…"