first mismatch at byte 0x1f000
On the 1280, the standard bootloader has a MONITOR mode, open up the serial port at 57600 and type "!!!" It easiest to just hold down the "!" and hit reset on the board. this will bring up monitor which will verify that its working properly.
I have never seen it mentioned anywhere either, I discovered it looking through the bootloader source code that came with v0018. It is specifically limited to the 1280. I have been working on 2560 quite a bit and have found lots of interesting things.
the "monitor" has a very short time out, there are several commands you can give it including "j" to jump to the user program.
This is what I am working on,
I am using Arduno v17 and an USB tiny ISP programmer.