Thank you for your response and for pointing out the aspects that needed clarification. Let me provide some additional details to paint a clearer picture. The issue at hand concerns a friend's Electrum wallet. Despite what it might seem, he has a very limited understanding of how cryptocurrency wallets function. After the wallet seemingly fixed itself from the initial parsing error, he was under the impression that the problem was permanently resolved, hence he did not think of resecuring the seed.
I have personally checked the backups he made, but they seem to be for a different wallet, as they all show an incorrect balance even after being fully synchronized with a full node.
He was using Electrum on a Windows platform, although I'm not sure about the specific version of the software he used. Importantly, after the wallet became inaccessible again, I attempted to load the wallet file with various versions of Electrum, but consistently encountered the same parsing error in each case.
I've also conducted extensive online research for a solution to this unique issue, but haven't found any methods that seem to apply or work effectively, which is why I'm reaching out for help on this forum.