proof of stake – How to ‘fix’ (or restart) a blockchain that stopped

I have a novice question. I’m working/experimenting with a small alt-coin project. It’s cloned from PIVX 3.3.0 and is currently 100% proof-of-stake. The blockchain has a current height of about 16000 blocks. The chain appeared to be working well for about 1-2 weeks. I have 4 seed nodes — 2 nodes are staking and 2 nodes are masternodes.

I modified one of my staking seed nodes. I removed the un-encrypted wallet.dat file from one staking seed node, and replaced it with an encrypted wallet.dat file. The next day, the blockchain stopped. I’m assuming the seed node that I modified died.

The daemons are still running at the seed nodes, but blocks aren’t generating. It’s been 4+ days later. I’m not sure how to diagnose this problem and how to begin fixing it. Information and/or techniques for repairing a broken chain appears to be very limited. Any help or advice is appreciated. Thanks in advance.