Had exact same problem with my 2014 Zuk a month ago. Two charged batteries, tic tic noise when trying to start, trim motor struggling, other electrics okay. Never had a problem before that.
My mechanic tested batteries cleaned all terminals, battery selector switch, earth lead, changed battery terminal connectors from wing nuts to direct to post.
Some connections had small amounts of corrosion but all clean now. No problems on last two trips.
Mechanic seemed to think alot of these types of problems come down to poor connections so I'd suggest checking there first.