Blown Teensy 4.1?

[Parzivil]

Hello all, I am in an interesting situation.

I came to continue work on my project today only to find that my Tennsy 4.1 no longers appears to power up. When plugged in with USB the light does not blink and it does not show up as a device on my computer. I checked the cable and the computer and both work alright. The Teensy was working perfectly yesterday and I haven't made any changes to the circuit it is connected to.

Probing around the Teensy I found that there is power being supplied as the 5v line provides 5v. None of the components are getting hot or look like they have blown, I have checked for shorts and didn't find any except between the 3.3v pin and GND.

I checked the circuit diagram and found that the 3.3v lines and GND are connected?

I would very much appreciate some help (as this yearlong project is due next week, pretty typical for this to happen at the last moment).

Thanks

*edit*
Looking further I have found that the F1 fuse next to the USB port gets a little bit hot but not blown.

 

[KurtE]

Have you tried the 15 second program button reset of the Teensy...

Once in awhile I get into a state where nothing appears to work... One thing with the T4.x, is that if you have it powered up and press and hold the program button on the board for about 15-20 seconds, the program led will blink... At that point release the button. The led should hopefully come back on and it will then hopefully reprogram the Teensy back to the original program it was shipped with.

When it completes hopefully you will start to get the blink program running...

Other tips up at:
https://www.pjrc.com/teensy/troubleshoot.html

 

[Parzivil]

Thanks for the advice, gave it a go and nothing. Further, inspection shows that the F1 fuse is heating up so that is another issue I have to look into.

 

[PaulStoffregen]

I have checked for shorts and didn't find any except between the 3.3v pin and GND.

I checked the circuit diagram and found that the 3.3v lines and GND are connected?

Obviously the hardware can not work if 3.3V and GND are shorted together!

Try measuring the voltage between 3.3V and GND while the power is on. If you see zero, or only several millivolts, that's a strong sign the short is metal, like stray solder or a piece of wire mistakenly fallen onto the board. Often these sorts of problems are fixable, if you can find the metal causing the short and remove it.

But if you measure something between 0.5 to 0.9 volts, I'm afraid that is a much worse sign. That type of "short" usually means one or more chips has internal damage. Those problems are rarely fixable.