Bricked Teensy 4.1 - cant restore to factory

R

Razon

Member
I bricked the controller by loading one of the examples from the FlexCan_T4 library without properly configuring the parameters before programming.
This is a 4.1 with the IMXRT1062 chip.

I'm able to get it to enter recovery mode by holding the button for 15sec and powering it up;
With the teensy loader in Manual the red led comes on for a while, then it goes out. Beyond that, nothing happens; no yellow led blink, and it doesn't show in the com port list. Cycling power doesn't do anything.
The first attempts I made were with the loader in Auto, and at first it seemed to work (yellow led started to blink), but it would stop after ~15sec and no comm port was shown (can't download the sketch again)

In one instance I got the loader to show the manual program and reboot buttons. I tried to download the Blink sketch, but it failed half way through and follow up attempts didn't work at all.
It's not clear how to enter this mode.

I found the procedure somewhat inconsistent; Does the controller need to be powered down for some time between attempts?
Sometimes nothing happens at the end of the 15 sec; sometimes the red led comes on briefly in a dimmed state, but when I let go the button it doesn't come on solid red indicating the controller is being flashed.
Any idea why all this this is happening?

IMG_7865.jpgIMG_7869.jpg
 
I seem to remember my one unit doing something similar once when my PC locked up during a program. I honestly don't remember what I did to restore it (I know, that's not very helpful - sorry!) but I remember having to repeatedly try some combination of holding the program button down for 15+ seconds, rebooting the Teensy, and attempting to program it once again before it finally popped back to life.
 
First, please be aware Teensy uses HID protocol in bootloader mode, and with the default LED blink program. So you should not see any COM port.

I know you said you were checking many things besides the COM port, but serial port was mentioned a few times too. Over and over we've seen cases where people mistakenly believed Teensy wasn't communicating only because a COM port didn't appear, when it was working properly but communicating with HID protocol rather than serial protocol.
 
From the screenshots, looks like Teensy is being detected by Teensy Loader.

Click Help and Verbose Information to open a window that shows detail (maybe too much detail) about everything Teensy Loader can see. That window has a "log" menu which lets you save it all to a file. You can also "clear", which might help if that window already has a lot of stuff accumulated.

The verbose info together with a precise description of the steps you performed during that logged info can really help to figure out what's going wrong.
 
Turns out the BGA chip is unsoldered and it has intermittent operation. I need to squeeze it or press it on the board for it to work.
This explains why I had such random results with the testing.
 
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