Alike with at least 2 previous replies, I have minimal electronics background design-wise, more confident in repairs.
There is a vast amount of resources now that just didn't exist, and this is an outstanding entry point. Here it's 5°F out. Sitting in the basement creating is superior.
I'll advise web-surfers, our US distributors will not be the most economical source to fill the BOM. Right now looking for an odd "D" battery holder; $4.60 one place, $28 another + 100 piece minimum. Caveat emptor. YMMV. IYKWIM. DAMHIKT.