QW-MS3010D 30V 10A Variable PSU Blown MOSFET

[RukyCon]

Hello again, I have this cheap 30v 10A variable power supply that died about a year ago, the issue with it is that one of the MOSFETs (IRF840) Blew its guts. Now despite this thing being cheap, the design may have saved the control electronics from being blown up, as they appear to be in good shape.

I may also replace some other components while at it and fix some of the bodge jobs so this thing looks nicer.

Being that this is my first time replacing a blown MOSFET, I may need a bit of help, so any help will be appreciated.
And hopefully, i don't make a dumbass out of myself again.