It's a 2018 crosscity e bike, battery as gone flat I did sell this bike and had lots of issues finally returned money even though the battery was left to go dead, we did warn the person, but what I woul ld I like to ask on here is how do I get to wake the battery up, I'm aware is 4 year old battery bike been road on 10 times if that, I'm looking how to get the battery working ( waking it up) then I can finally try sell the bike, can anyone let me know please how to do this or if anywhere I can sell the ebike when fixed still looks new thanks in advance any help will do please