I am far from an expert also, but have some experience with my own
RAID 5 array using mdadm.

It looks like one drive is giving you an issue when you are trying to
force the assembly:

mack ~ # mdadm -A --force /dev/md0 /dev/sd{a,b,c,d,e}3
mdadm: superblock on /dev/sdd3 doesn't match others - assembly aborted

Have you tried assembling the array degraded to see if you can force
it without sdd3?  I don't know if this is the best solution, but if
that works, you can then readd sdd3 and have the array rebuild.