Found my missing Kobo Libra 2 after over 2 years! Battery advice?

My kobo libra 2 went missing when we moved house. It just turned up today in a box hidden in the spare room! It’s dead of course so I’m charging it now and it turned on. Software is 4.30.18738 from Oct’21. It’s been kept at room temperature in its case for all this time. How badly affected do you think the battery will be compared to before? Is it easy to replace the battery? I’m so pleased I’ve found it and I will be using it, but I’d like to be prepared for what I can expect from it for the next 2-3 years or so.

Thanks in advance 😊