The T1 has an ICM-42607-P IMU with the same address as a DS3231 RTC.
This completely breaks the clock on the T1. Reading the time results in
a garbage value, causing all sorts of strange issues. The time never
advances, which breaks logging in to repeaters (due to their time-based
replay protection).
This simply disables the probe on the I2C line. The DS3231 doesn't have
a WHO_AM_I register that could be used to prevent misidentifying it, so
this simpler fix is used.
SPI pins that are set to -1 cause OOB reads on NRF52. The unused Serial2 pin definitions were removed to avoid potential issues with the Uart framework.
Huw Duddy