What does ST-LINK/V2 saying "unknown target connected" mean?

[JBonn]

Unplugged JTAG from prototype unit for hand held testing. Need to plug back in for more code development . Using a STM32L476_LQFP64 chip. Did upgrade to STM32+STM8 Debugger from V2.J24.S37 to V2.J37.S37 and back. Neither version worked. Is there a "target list" that got deleted somehow?

[Tesla DeLorean]

No, your device is simply non-responsive.

And code in there to put the device into a low power mode, or interfere with the SWDIO/SWCLK pins?

Is NRST wired?

Try strapping BOOT0 High on your board, if that connects and you're able to erase, then something errant in your code.

[JBonn]

Tesla,
Thanks for your reply.
My device still runs (batteries) the last load put in it before unplugging for hand test. It drives an OLED display, buttons work, Etc. I can turn the unit on/off.
But, I cannot clear or access the chip anymore.
There are only five wires coming out of the ST-LINK V2 that are sent to the chip; (1) GND, (2) TCK_SWCLK, (3) TMS_SWDIO, (4) TDO_SWO, and (5) NRST.
If it is a wiring problem, one of these five must be broken.
If it is a code problem, I have not been able to identify it.
Any suggestions, especially code related?
Thank
Jerry

[JBonn]

Tesla and all,
Found a project that was over 1.5years old that loaded and ran.
The problem was something not yet discovered in the project settings.
In addition, found 10 of my current projects that were working also had random insertions of two letters (e.g. ab) in various modules.
I will not close this inquisition.
Thanks, Jerry

[Tesla DeLorean]

Watch that things like CubeMX don't slip a disable SWD/JTAG Debug Option in on you.

Grep/Find-in-File GPIO_PIN_13