Not sure if it is the owner or the tenant, but not the Strata. Get ready for the price to be well over what the remotes are worth. This is why so many people I suspect never replace them unless they have nothing else left.
You may be able to go to somewhere and just replace the battery. However I’m sure legally no-one is supposed to tell you to fix yourself as it could be “unsafe” however my husband who is a handy sort of guy bought a new battery and replaced it for me. It was somewhere like Jaycar or similar. Take in the remote and they may even do it for you. You may need a Philips head screwdriver to open the remote as well often is the case with items like these, often parents these days might have one due to toys having lots of batteries and it stops our clever clogs’ being able to open them with small items as batteries are dangerous to small children if ingested, even cheap $2 shops have these similar type screwdriver heads…
Perhaps check your lease if any mention is made about cost etc. and if the just have to supply you a remote, whether working or not etc. I needed to get the details from our Strata who we use – as it will be someone who has a monopoly usually for the building for ordering – as imitations don’t work, or won’t work for long suggest not to waste money on those, no matter how tempting.