I had closed my lightening channels a while back as no one was routing any transactions over my channels. I left the BTC in the on chain bitcoin wallet hoping to give lightning another try at some point. The node sat running and I didn’t think anything of it until recently and that’s when I discovered I couldn’t get into the node via Umbrel and then tried seed phrase. Would Umbrel be able to assist or do I consider this a donation to the cause? 

 If the seed phrase is correct you should be able to recover your sats. 

This link has a lot of possible scenarios that you could try:

https://community.umbrel.com/t/how-to-restore-your-node-wallet-updated/3602