I have a BMC TM SLR01 (2012) so fairly old, with 1st gen (I think) Shimano Di2. The rear derailleur stopped working at the weekend, but the front derailleur was. Now they've both stopped working. I charged the battery, but nothing, no lights on the junction box. I bought a new battery, but that hasn't fixed the problem. I did notice a tiny bit of moisture on the inside of the battery when I removed it. Could this have fried the entire system? What troubleshooting steps can I take?