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Assuming your battery is okay and the wiring harness to the EBCM is okay, then your EBCM has failed. Most likely either the power relay failed or has broken solder connections to the PCB. Perhaps the last repair shop's work was not as good as it should have been.
Highlighted code bove is the main power relay in the EBCM. ABSOLUTELY will illuminate the ABS/AH/TC lights on the dash and disable ABS. TC and AH for the current ignition cycle.
C0690, C0691 and C0615 are all issues with the electronic suspension control. Your profile says you have C6Z06 shocks. Most likely you did not program out the F45 RPO or if you used resistors or sims they have failed.
Assuming your battery is okay and the wiring harness to the EBCM is okay, then your EBCM has failed. Most likely either the power relay failed or has broken solder connections to the PCB. Perhaps the last repair shop's work was not as good as it should have been.