To help find the right fix, could you share a few more details?
Take it back to the repair shop immediately. It is highly likely they installed a low-quality screen, or the flex cable is not seated correctly.
Why does this happen on Samsung devices more than Pixels or iPhones? The answer lies in Samsung’s aggressive customization of Android through the OneUI interface. invalid ppi samsung
Are you seeing this error after a or after a physical repair ? SAMSUNG A12 INVALID PPI
Crucial security or bootloader partitions have become unreadable or damaged, preventing a "normal boot". Hardware Instability: To help find the right fix, could you
You do not need to buy a new phone. You need to fix the density mismatch. Here is the technical hierarchy of solutions:
Attempting to install custom recovery programs, custom ROMs, or incorrect regional firmware packages can permanently break hardware ID validation loops. 4 Methods to Resolve the "Invalid PPI" Error 1. Perform a Hard Hardware Reset Why does this happen on Samsung devices more
The error is a critical firmware and hardware initialization failure that locks Samsung Galaxy smartphones into a boot loop or prevents them from accessing Download Mode. It typically surfaces after an interrupted software update, a failed flashing attempt using unauthorized tools, or physical hardware degradation.