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Re: No Boot-Up (after spikes)
I will leave the recommendations for a new Raduino to others.
In the mean time, and as an alternative to the chainsaw (hihi), since you seem to have i2c activity you could, if you want to use non-gui style command line interface, install the diagnostic software in the Raduino to check that the communication with the si5351 is possible.
The readme file contains the settings for the Arduino IDE terminal that is used to control the tests.
The core system tests (option 1) will tell you if:
a) the i2c bus is locked
b) the si5351 chip is not found at the expected bus address
c) the Nano can't write to the registers of the si5351 chip
Best done with the Raduino removed from main board.
We can then take it from there.