Lots of issues while trying to achieve higher temperatures

Question

lI have an older spool of PLA filament which has absorbed some moisture and doesn't print well at normal PLA temperatures, but does at higher temps like 220+ °C. Attempting to print at this temperature range has led me into a number of issues:

1. M112 shutdown thermal runaway. The print appeared to be going perfectly fine until the firmware shut down with M112 Thermal Runaway about 15-20 minutes into the print

2. Attempting PID tune with M303 E0 S240 C20 failed with PID Autotune failed! Temperature too high

3. Re-attempting PID tune with M303 E0 S235 C20 resulted in OctoPrint losing the serial connection: State: Offline after error Too many consecutive timeouts, printer still connected and alive?. Autotune appears to have succeeded on the firmware,

To mitigate issues with the serial connection, I've switched to a 3 ft long micro-USB cable with ferrite core and gold-plated connectors. I''ve also taped the 5 V pin. The voltage at the outlet connected to the printer is around 121 V.

serial.log

Is there a way to ask the firmware to provide more details before crashing with an M112 thermal runaway error?

What could be causing the failure to PID autotune and frequent serial disconnects at higher temperatures?

This is an Ender 3 Pro with Marlin based on the bugfix-2.1.x branch.