Stray Voltage on Custom PCB
I don’t see anything inherently wrong with your schematic or layout at first glance. This leads me to suspect that you created a short during assembly.
Something that I haven’t seen you mention is that you performed continuity checks between traces at every component lead, both before and after assembly. This is a critical step before applying first power: You want to make sure that the bare PCB is correct, and you also want to make sure that you didn’t inadvertently cause unintended connections with a stray pin, wire, solder glob, or even flux residue. (The latter is particularly sneaky since flux is translucent and may contribute a low-resistance path rather than a full short.) Also double-check for correct and correctly-rated components (like your transistors - are they EBC or CBE?) and reversed components (e.g. diodes).
I would suggest a full continuity check (or ‘ohming out’) as your next debugging step. I’d also recommend taking well-lit, high resolution photos of both sides of your board, preferably from multiple angles, to give both yourself and us a chance to examine it for potential problem areas.