Pi won't boot after removing reference from Cayenne web dashboard

raspberry pi 3+
raspbian Jessie (noob)
32GB microSD

Had the dashboard working with my pi for months. Decided to remove its reference from the Cayenne web dashboard. Immediately after doing so, the pi shut down automatically and now it won’t boot up. Seems like a partition got corrupted?. I can put in an old microSD card image from a backup I made a month ago and it will boot up. But then I’ve lost a month’s worth of work. I don’t know the raspbian boot up process well enough to know what to do to get the microSD card back to working. BOOT: two red lights; then one flashes yellow 3 times, back to red, flashes 3 times yellow, then both solid red.

3 flashing yellow lights seems to be an issue with the start.elf file. Put the SD card in another computer and open the boot partition and rename start.elf to start.elf.new then rename start.elf.new start.elf. Put the card back in the Pi and try to boot again. If that doesn’t work let me know.