If you can spend the change output from the channel open transaction, you could create a new transaction with a much higher fee that spends the change. This would incentivize miners to confirm both transactions to get the higher fee from the second one. Or, You can try to broadcast a new transaction that double spends the same inputs but with a higher fee. This would be an attempt to "replace" the initial transaction. However, not all nodes will accept or propagate double-spent transactions, and some miners might not mine them. If the channel is showing as pending in your Lightning node, but the transaction doesn't exist in the mempool, it might be possible to force close the channel. However, this typically requires the channel to have been fully opened at least once, so it might not be an option in your case.