Hello,
When you open a file manager and check the MSD memory, provided by on-board ST-Link, then you will see the memory has just 32Kb or something like that, I think.
This is usually caused when the target MCU is not properly powered or wired with ST-Link. But in the context of overheat on the chip that seems like you have a short circuit somewhere.
STM32 Nucleo-32 boards (MB1180) - User manual
I do not know how you powered your Nucleo, but you probably need to check the board and Voltage regulators what are responsible for power for MCU.
- U6 - LD1117S50TR
- U3 - LD39050PU33R
For verifie your MCU is not dead you can remove a small jumper SB14 and put 3v3 from another source to 3v3v pin. Or remove small jumper JP1 and bring 3v3 on of its pin.
I had same on Nucleo-F303K8, after I ordered and replaced both regulators problem was gone.
BR, Jan