S10E Will Not Boot After Battery Replacement

TLDR:

I verified that my device's battery, screen, vibrator, and power button are functional. However, my phone is currently off and is unresponsive to all inputs (power button, charging, volume down + bixby + cable connected to laptop). If I freeze the device, it will boot for a few seconds before shutting off again.

Long Post:

Context: My device is just over 6 years old. I was watching a video on it when it abruptly froze and entered a boot loop. When the boot loop concluded, the phone remained off and unresponsive to the power button.

Research:
I found out from a couple Reddit threads that the issue could be with either the battery or the motherboard. A commenter suggested freezing the phone and seeing if it will boot. I attempted as such and to my surprise, the phone came back for ~50 minutes before crashing and reentering the boot loop.

What I attempted:

This finding indicated that the issue is with the battery. I ordered the S10E battery replacement kit from iFixIt and performed the replacement. I verified that the new battery was charged (4.095V). Unfortunately, my phone still did not turn on after installation. Of note, the old battery was in fact bad; I measured its voltage at 2.5V.

I attempted to freeze the device as a last resort, and to my surprise (seriously, why does freezing enable a boot?), the device booted into recovery mode. I then was able to select the "Reboot Device" option and waited for my phone to boot. My phone made it to my lock screen but immediately shutdown again and became unresponsive. A positive take away is that I proved that the power button and display were not damaged during the battery replacement process.

I read in another iFixIt thread that I may need to reconnect the old battery and then reconnect the new one after it. As strange as this seems to me, I attempted it to no avail.

Observations:

The device draws 500mA when plugged into a charger. When the new battery was installed, the device's motherboard did noticeably heat up. Attempts to turn the device on would again result in the motherboard heating up. I cannot replicate this after I froze the phone.

Plugging in the device does not result in the expected vibration coupled with the battery charging graphic. The vibrator was responsive when the phone booted after it was frozen.

My Request:

I am now out of my depth and would greatly appreciate assistance. I want to preserve my S10E for as long as possible. It is perfect for my needs and there are no modern options that provide the qualities I like about it (compact, SD card, headphone jack etc.)

Thank you in advance.