HOW did you "check"?
Not trying to be flip here, but some kinds of "checking" can fail to actually detect a problem. I've told this story before but I'll pull it out once again...
I was in the middle of a big project and a neighbor wanted to borrow my B7800. That tractor wasn't starting and I couldn't readily determine why: I really had ZERO time to be messing with it (I think the clock was running on some rental equipment I was using). Another neighbor volunteered to troubleshoot. That guy eventually gave up. I believe that he said the fuses were all good. When I finally got around to looking at the tractor myself I pulled and TESTED, with a meter, each fuse and found that one was bad- yes, THE FUSE that was responsible for starting (fuel solenoid and such, I believe). The fuses LOOKED good, but clearly that was an insufficient assessment.
CHECK YOUR GROUNDS! (also, those relays, clean off the lugs really good- pictures show poorly seated relays- it's possible that one of the relays is stuck- poor connection can cause it to over-heat, which then will make them stick; sometimes slamming the relay around, smacking it, can help- better is to just test them)