I was using such an extension shield:
It is built using an MCP2515 (datasheet) controller and a TJA1040 transceiver.
The resonator on it has undefined signs, so I wanted to use a logic analyzer (DSLogic plus) to check its frequency (maybe it wasn't a good idea from the very start).
So I connected it to the OSC1 input of MC (only later I realized, that I could have used the crystal output soldered on the bottom of the board, and maybe nothing wrong would have happened).
But it seems I suddenly soldered the OSC1 and Vss (ground) pins on MC together, so now it is not working, and I wonder if it is just the crystal, and if I can exchange it, or if it is MC and nothing would help.
P.S. here is a comparison of Arduino Uno and that shield's clock frequencies after the last one being broken.