Try to replace the MBR745,or maybe it's not so good isolated from heatsink - and therefore causing to short-circuit.
Also,it may be a problem of power-good circuit. Disconnect the input to CMOS4049 and then try to measure the voltage.
About LM2587-3.3 - you want to use it for 3.3v? It can only supply 1.5A...not like MAX788.
And try to connect your whole setup to car battery,and then see if you have problems operating the PSU.