Please Help — Ender 3 Pro SE Bed Won’t Level After Reassembly

Hey everyone, I’m really stuck and could use some guidance.

I have an Ender 3 Pro SE that was working fine until I removed the heated bed plate and the Y-axis carriage plate underneath it (the part that rides along the rails). After reinstalling everything, I cannot get the bed level again no matter what I do.

When I run mesh leveling, the numbers are wildly off across the grid. I’ve tried adjusting things repeatedly, but it just shifts the unevenness somewhere else instead of fixing it. The bed refuses to sit straight.

For reassembly, I tightened the screws in this order:

• front left
• back right
• front right
• back left

Even tightening them gradually and carefully in that pattern didn’t help. This isn’t an old printer either — it was working fine and then suddenly this started happening after I took it apart. I’ve also already checked the gantry, and it’s fine, so I don’t think that’s the issue.

Visually, it does look like the Y carriage might be tilted ever so slightly to the right, which makes me wonder if something there is misaligned or seated wrong.

I also swapped from a glass bed to a magnetic bed, hoping that might help flatten things out, but it didn’t change the issue.

Questions:

• What should I check after removing/reinstalling the bed and Y carriage?
• Is there something that commonly gets misaligned or seated wrong?
• Could this be something with the Y carriage or rails instead of the bed itself?

Please help me get this thing leveled. I feel like I’m missing something obvious and it’s driving me nuts. Any advice is appreciated.