I have a teensy 4.1 and when I turn it on, the large black square at the center of the teensy gets very hot. Is this normal? I'm afraid of frying the teensy. Thank you.
Everyone has their own definition of what's hot
It will get warm but unless you're overclocking it it shouldn't get hot. It can hit the same temperature as the outside of a mug with a fresh tea/coffee in, it should never get to the point it's uncomfortable to touch.
You started 2 conversations. Your other message says 4 blinks. Is this the same Teensy 4.1 board, or different boards?
To answer only this question, normally the main chip gets "warm" but it should not be "very hot". Often this sort of problem means the hardware has been irreversibly damaged. The first step to troubleshoot is to disconnect all external circuitry and use a voltmeter to measure the 3.3V power. Zero or very close to zero volts usually means something metal is shorting the power. Sometimes metal shorts can be fixed if you can find and remove the metal object. A low voltage, like 0.3 to 0.9, usually means a semiconductor short where the damage is inside a chip. Usually a semiconductor short is not feasible to repair.