I check the forced close transaction and it is confirmed, my output not spent. I guess that using backup seeds alone may help to recover fund, I don't know how to get the channel backup file from LND start9 yet.

haimot

lightning

Recover a forced close channel

After the channel close is confirmed you can use the seed backup to restore the node into a fresh LND install. Not in strt9 just install LND directly on a node so you can use commands and restore the seed. 

Not sure if you can access lncli from start9. I know you can exit the gui menu and use commands from a raspiblitz if you still want to use some kind of pre roll node. 

https://github.com/raspiblitz/raspiblitz

Anyway the point is to learn the commands:

https://docs.lightning.engineering/lightning-network-tools/lnd/wallet

 https://docs.lightning.engineering/lightning-network-tools/lnd/disaster-recovery