Thanks for the suggestion and general advice. I added 100uF and 1000uF electrolytic capacitors to the board where the 3V3 comes in which is about 1cm from the esp32 and the bulk SMD ceramic decoupling capacitors, 10uF, 1uF and 0.1uF. The pins also have closer 0.1uF decoupling capacitors ...

I have a cheap programmable power supply generating the 3V3.

I am trying to get a very basic custom pcb using an esp32-s2fh2 chip working, schematic attached. I am holding the switch down to bring strapping pin GPI0 to ground during power up to select the boot mode. After initial attempts to communicate with the chip failed, I verified the oscillator was at ...