Should the high voltage mosfet be fastened down, grounded or have a heat sink attached? Everything is assembled right but it doesn't turn on. All that's in the manual is just the mosfets not fastened down.
No need to do anything with the MOSFET unless you really want to, It's fine just standing there on its pins. A heat sink isn't usually necessary but feel free to put one on if you want.
BUT - if you put a heatsink on either the MOSFET or the 7805 you absolutely must NOT create a connection between the metal tabs of the 2 parts!!!! Use separate heat sinks that don't touch each other, or use mica insulators between the tabs and the heat sink(s).
Look into it later when the dust is clearing off the crater.