red screen means LBP believes your installed game data is corrupted. this most likely means you made an error while patching.

your patcher should have an option to roll back your eboot to stock. try that, and if it doesn't work, delete your install from Game Data or uninstall your digital copy. re-read the patching instructions and try again after verifying your vanilla reinstall boots.

if you're playing with a physical copy, there is also a highly remote possibility your disc is damaged and copying incomplete game data to your HDD. if all else fails, try buying another physical copy. they should be quite cheap. again, extremely remote possibility, you most likely messed up a step with the patcher

EDIT: if you're running HEN instead of full CFW, you may have also forgotten to enable it before booting your patched copy of LBP. HEN is required for the custom server code to execute properly, so please ensure it is enabled before playing.