CR6-SE fails to heat hotend to set point TL;DR - Please help me rebuild my CR-6 SE so that I can move on

Here's a link to the latest issue that I had to make proof of in a video: CR6-SE failed
Basically, it's failing to reach/maintain temperature (set point of 240 °C, fails to heat above 230 °C), issues start to happen at temps as low as 210 °C.
Creality support is evasive/dodgy. First, they want to see a video proof for the problem reported, and after a while and emails from me asking, suggested something obvious (set temp to 200 °C).
And without any video, they don't respond. Just like last time when I ran into the defective/burned power switch and failed bed leveling.
If you have some spare time, please quickly check the video and provide some feedback.
I already fixed the burned power switch and auto-leveling (Creality ignored me, so I got the parts from Amazon).
This is the last issue that I need to do a &quot;mercy&quot; fix, so that I can either repurpose it or, just give it away (but I still have to make it working again and safe!).
I already placed an order for an i3 MK3S+, should've bought this in the first place to help me study 3D modeling, not working my degree towards fixing Creality printer failures :)
Thanks in advance.
My troubleshooting steps so far after a screw fell off during print:

Disassembled the hotend: found heater block loose, screws were bent and somewhat stripped
Heater resistor has a bad crimp
Thermistor is reading temp, but I don't know if it's accurate (don't have a multimeter+thermocouple)

Ordered a hotend from AliExpress, hopefully, that's it
Perform PID calibration procedure for hotend using G-code 'M303' with nozzle fans turned off completely.
You may use detailed guidelines from AK Eric's blog, RepRap wiki or 3DMaker Engineering.
If this will improve or clearly change the situation, but you still observe some issues during or after tuning, review other posts for troubleshooting. For example: large initial overshoot, no oscillations, struggle to fit into functional range or narrowed down hardware issues of incorrect heating cartridges.
When succeeded, you should repeat the procedure with fans enabled at the regular speed you use during printing.
PID calibration can be performed from Marlin's LCD menu (Configuration &gt; Advanced Settings &gt; Temperature &gt; PID Autotune E1). It will allow to select target temperature, but not number of tuning cycles. It is only accessible when PID_AUTOTUNE_MENU is enabled in firmware settings (Configuration.h):
//#define PID_EDIT_MENU         // Add PID editing to the &quot;Advanced Settings&quot; menu. (~700 bytes of PROGMEM)
#define PID_AUTOTUNE_MENU     // Add PID auto-tuning to the &quot;Advanced Settings&quot; menu. (~250 bytes of PROGMEM)