Modern phones aren’t designed to be repairable. So repairs going wrong is not rare (is not frequent either). I’ve read that refurbished offerings are actually viable, since they’re usually phones with nothing wrong, just got returned and aren’t new anymore. Samsung sometimes offers this when able.

If you want a real repairable and made to last phone, the fairphone exists. Recycled materials and all that.

Other than that, second hand depends a lot on where you live. If you can search a high income wealthy market space, then the chances of finding super cheap, recent and perfectly functioning phones is higher.