Burned wrong bootloader

[Perkuuns]

Without knowing what I'm doing I pressed "Burn bootloader" on Arduino IDE. Now I cannot upload any sketches to my Teensy 2.0
After few hours of researching I understood what I've done.
Is there any way to fix the Teensy? Or at least any way to upload sketches?
I have Arduino Mega and Arduino Nano. Is it possible to fix it (at least partly) via Arduino ISP?

 

[Theremingenieur]

On a genuine Teensy 2.0, the boot code is protected and can‘t normally be easily overwritten. If your accidental wrong action bricked it, though, odds are good that you can get it running again, following the troubleshooting instructions on this website: https://www.pjrc.com/teensy/troubleshoot.html

But if you don‘t have a genuine Teensy 2.0 but a cheap illegal China clone, then, all you can do is throwing it away and buying a genuine one from an authorized reseller.

 

[GremlinWrangler]

Assuming the actual IC is ok you can probably do the 'uno as ISP' thing and program that way, but that looses a lot of the Teensyness. If you think you have a phony, compare it to the PJRC reference card photos looking at the LED, the button and the silk screen or post a photo here.

 

[PaulStoffregen]

If you had only a normal USB cable between your PC and Teensy, then "Burn bootloader" can not harm your Teensy. Sure, something got messed up (and we can try to help you resolve that), but I'm here to tell you with certainty that you can't actually alter the bootloader on a genuine Teensy using "Burn bootloader" when only a standard USB cable is used.

However, if you connected a ISP programmer between your PC and Teensy, which usually involves making a special 6 pin cable since Teensy doesn't have the mating 6 pin ISP header, then "Burn bootloader" could indeed destroy your board's bootloader. If you did that, I'm afraid the answer is you're out of luck to restore it (but you can still continue programming the chip with your ISP programmer cable).

Likewise if you have a counterfeit Teensy, they can be quite fragile. The Chinese companies who make those counterfeits don't pay attention to details like making the board robust. Their entire business model revolves around you not being able to contact them, so they can enjoy zero support & service cost.