New Bambu and Ender owners do the same three things in week one:

They slice a huge model. They skip washing the bed. They tweak five settings at once.

A dirty PEI sheet will ruin a perfect STL. So will a first layer that's 0.3mm too high. Spaghetti is almost never "the file is bad."

Do this instead:

• Print something that finishes in 20 minutes.

• Use the stock PLA profile. One change at a time.

• If it fails twice, stop and look at the first layer, not Reddit.

I keep a starter pack of print-ready files for that first week, and a separate 1-hour live debug if you want someone on the slicer with you. Files and repair are not the same product on purpose.