Try also with '--quit' option, which allows you to abort the current operation and further clear the sequencer state.
--quit Forget about the current operation in progress. Can be used to clear the sequencer state after a failed cherry-pick or revert.
--abort Cancel the operation and return to the pre-sequence state.
use help to see the original doc with more details, $ git help cherry-pick
I would avoid 'git reset --hard HEAD' that is too harsh and you might ended up doing some manual work.