Reboot / display resolution issues

[TedMaul]

Pi Model or other hardware: 4B
Power Supply used: NorthPada
RetroPie Version Used: 4.8.2
Built From: Update from image on RetroPie website

An attempt to solve an issue with my Pi not rebooting when requested (hangs on a no signal screen) has led to further problems with it now weirdly forcing a 640 x 480 resolution which it previously didn't do.

/boot/config.txt is here:

# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See link above for details

# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1

# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
# disable_overscan=0

# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
overscan_left=-10
overscan_right=-10
overscan_top=-20
overscan_bottom=-20

# uncomment to force a console size. By default it will be display's size minus
# overscan.
framebuffer_width=1280
framebuffer_height=720

# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode (this will force VGA)
#hdmi_group=1
#hdmi_mode=4

# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2

# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
config_hdmi_boost=7

# uncomment for composite PAL
#sdtv_mode=2

#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Uncomment this to enable infrared communication.
#dtoverlay=gpio-ir,gpio_pin=17
#dtoverlay=gpio-ir-tx,gpio_pin=18

# Additional overlays and parameters are documented /boot/overlays/README

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

[pi4]
# Enable DRM VC4 V3D driver on top of the dispmanx display stack
dtoverlay=vc4-fkms-v3d
max_framebuffers=2

[all]
#dtoverlay=vc4-fkms-v3d
#overscan_scale=1
#enable_tvout=1

The display is a Samsung HD-ready TV (probably 10-15 years old) but has worked fine until now.

Applying:

hdmi_group=1
hdmi_mode=4

Shows the display properly, but then doesn't allow access to the X desktop which it did previously (TV errors out with a "mode not recognised" message). X desktop will not work with this new 640 x 480 resolution it has forced on me either. I haven't attempted any ROMs yet.

On top of all this the reboot still hangs as if the Pi has shutdown.