Transistor in the Darlington pair getting burned?
simulate this circuit &ndash; Schematic created using CircuitLab
No problem using 330R instead of 1.5k

But changes for hFE of 100x100 =10k with EMI from relay wires turning relay on with spurious noise during shutoff can cause spurious load currents and VI power drain might exceed 300mW on transistor. i.e. Darlington  may be overkill and too sensitive near relay coil EMI. 

Normally a resistor across 2nd Vbe is all you need to shunt Q1 leakage.

This is just a SWAG.