ADB/fastboot over Serial/COM ports?

ADB/fastboot over Serial/COM ports?

Long story short, I messed my phone up and it's stuck into a bootloop
(splash screen -> recovery mode -> splash screen ad infinitum). The usual
ways of connecting to it using adb or fastboot don't work anymore -- They
won't detect the phone in any way. I am connecting the phone to my Windows
PC using its USB cable. The only links I get to it are:
3 empty and useless removable devices pop up in My Computer for a few
seconds during the bootloop. All of them ask me to insert a disk. One of
them shows up as a CD-ROM drive and the other two as generic removables.
The CD-ROM drive, when the phone used to work, was used to mount some
driver installing software. The other two I'd assume to be links to the
internal and SD storage.
In Device Manager, under "Ports (COM & LPT)", 3 new devices show up at the
same time as the ones above. I cannot post pictures yet so I am going to
type them out:
Coolpad Android AT USB VCOM (COM7)
Coolpad Android Diagnostics USB VCOM (COM10)
Coolpad Android NMEA USB VCOM (COM9)
These three seem like my only means of making a connection to the phone.
There must be a way, what use would they have otherwise?
I have to also mention that I've tried all of the power on button
combinations and I can only manage to get into the useless stock recovery
mode. The phone's bootloader is also locked.
The phone is a Coolpad 7560U.