That's at least two of us this week then 🙃 See earlier in thread. For me it was my battery pack jump start booster - which ironically (or not) was not actually any good in my situation (completely flat battery, needs a proper charger instead). Good luck with getting your battery/car back to health too.
Currently I have borrowed a friend's CTEK MXS 3.8 charger on it. All good so far, working it's way through the levels but am able to lock/unlock the car by the fob and no alarm issues. My cheaper 'one trick' trickle charger is on the way.