Autonomos dead...more so than normal this time

So I have learned over the years to include the extra 5 seconds at the start of the sketch and how to reset using the J1 pin. However, it looks like I may have just killed 2 boards with one program tweak. I use the RTC to manage waking/sleeping. I added a line to try attaching an interrupt (rtc.attachinterrupt()) and now the board will not activate a port on any machine I connect to. I managed to do this to 2 boards when testing the issue. I have a third board and don’t want to kill it too! It doesn’t matter how many times I short out the pin on J1 or hit the reset button…or unplug and plug back in…nothing. Both boards are completely unresponsive. They do have a fast blinking light (charging I assume), but they are stuck. Any ideas? I saw one older thread where two users reported this, but never reporting finding a fix.

Did you try these fixes?

I did. My third board comes up on the machines without issues, so some of those steps are mute. However, they have all been tried multiple times.

I am going to try ordering one of the programmers in an attempt to resurrect. If anyone has any other ideas, I would love to hear them!

Ok, so I now have the JLink programmer referenced above. Any quick and easy paths to programming? I am starting to poke at it…loaded Atmel 7, the jlink USB drivers, etc. Before I got too deep into it, I thought I would check here to see if anyone had experience. Thanks!