[General Questions and Answers] tab328:
Mmm, so right after posting, I figured out that I had to change directory to one of the commands listed in the first help in order to issue commands from the sub-help of each one instead of using them as arguments. EG: cd pmx [enter] pattern 1 [enter] would turn on the test pattern instead of pmx pattern or pmx pattern 1 or pmx -p and other such variants. There's probably a guide for this out there somewhere but most of my searches just turned up historical info on German submarines... Oh, and this thread which is kinda along the same lines: https://xdaforums.com/android/software/rooting-mediatek-based-linux-smart-tv-t3150281

I guess now I just have to find which setting(s) fix my apparent problem, then I'll need to append the firmware, assuming I can't do it from the serial console. And that'll be the part I definitely need help with.

Maybe I can just use commands to do this, but I don't know what most of this is, and my searches aren't yielding much... That said, I can run the commands and post back the results since I don't expect anyone to have this same model.

Here's the menu and submenus with my comments in quotes:

cd: Change current directory "Figured out this one"
do: Repeat command "Self explanatory"[HIDE]
Usage: do loop cmd ex: do 10 read 0x200 0x10
CLI Command Return Value (-1)[/HIDE]
alias(a): Add/Show current alias "not quite sure what this does"
read(r): Memory read(word) "I guess these are self explanatory? no output if I just run the commands"
write(w): Memory write(word)
basic_(b): basic command [HIDE]
[Help]
stop: Stop RS232 transparent mode
sv: System mode detection
version(ver): System version/build date
reboot: System reboot/restart
getpllclk(gpc): close loop, gpc [cpu|sys|ps|vo|adc|b2r|apl1|apl2] [[band num]]
backup(bk): backup command
[/HIDE]
mtktool(0): mtktool command "the help kinda explains?[HIDE]
[Help]
et: Enter RS232 transparent mode
ft: Set RS232 factory mode
st: Stop RS232 transparent mode[/HIDE]
customer(cust): Get customer name "returns [TPV] and nothing more"
pmx: pmx (scpos) command "looks promising?"[HIDE]
[Help]
enable(e): enable/disable LVDS
pattern(p): enable/disable test pattern
list(l): show panel list
query(q): dump pmx(scpos) info
set(s): set parameter
[/HIDE]
musb: MUSB command "probably controls the usb port on the back?" [HIDE]
[Help]
debug_on(d_on): MUSB.d_on
debug_off(d_off): MUSB.d_off
debug_level(d_l): MUSB.d_l
init(i): MUSB init
speed(speed): MUSB speed
hmsd(hm): MUSB host msd test
htst(ht): MUSB host compilance test
suspend(s): USB bus suspend
resume(r): USB bus resume
[/HIDE]
sif: Sif command "I know what edid is basically, maybe I could make the computer think this is a non-hdtv type connection?"[HIDE]
[Help]
init(i): Sif init
read(r): Sif read
write(w): Sif write
writebyte(wb): Sif write byte
hdcp: Sif write HDCP SRAM default value
rhdcp: Sif read HDCP
wbhdcp: Sif write byte to HDCP
rbhdcp: Sif read byte from HDCP
wallhdcp(wah): Sif write all 320 bytes to HDCP
rallhdcp(rah): Sif read all 320 bytes from HDCP
edid: Sif write EDID default value
redid: Sif read EDID
walledid(wae): Sif write all 256 bytes to EDID
ralledid(rae): Sif read all 256 bytes from EDID
tunerread(tr): Tuner I2C No-sub-addr read
tunerwrite(tw): Tuner I2C No-sub-addr write
multipleread(mr): Multiple sub-addr I2C read
multiplewrite(mw): Multiple sub-addr I2C write
scan1(s1): Scan BUS0 (System I2C)
scam2(s2): Scan BUS1 (Tuner I2C)
sif_x_read(xr): fully functional sif read
sif_x_write(xw): fully functional sif write
edidreadbyte(edidrb): edid read byte
[/HIDE]
eeprom: Eeprom command "there's an 8 pin eeprom on the mainboard" [HIDE]
[Help]
readbyte(rb): eeprom.rb [eeprom-offset]
writebyte(wb): eeprom.wb [eeprom-offset] [byteval]
uartwrite(uw): Get data from Uart and write to eeprom.[/HIDE]
nim: Nim command "I assume this controls the onboard tv tuner"[HIDE]
[Help]
id: Set Tuner ID
ver: Tuner version
dtd: Nim dtd
atd: Nim atd
d_l: Set Debug Level
go: Start Nim
up: Channel Up
down: Channel Down
channel: Channel Set
freq: Freq Set
init(i): Nim init
open(o): Nim open
close(c): Nim close
setcable(sc): Nim set cable parameters
setBW(sbw): Nim set BW
getcablelevel(gclv): Nim get cable signal level
getcablesignal(gcsc): Nim get cable signal parameter
getcablelock(gclk): Nim get cable lock status
detachmw(dm): Nim Detach MW
detachi2c(dei2c): Detach Tuner I2C
[/HIDE]
ir: Ir command "InfraRed as in the remote I s'pose" [HIDE]
rx(rx): RX commands
[/HIDE]
rtc(rtc): RTC commands "returns [HELP] and nothing more. Real Time Clock I'd wager unless that has another meaning"
aud: Aud command "onboard speakers and other audio functions"[HIDE]
[Help]
ptsdly(ptsd): Delay audio startup by increasing PTS
dd_banner(banner): DD banner turn on for DD Test
spdif: spdif command
adac: adac command
interdac: inter dac command
dsp: dsp command
uop: audio uop
cfg: configuration
t: test
Clip: Aud Clip
factory(fac): Factory mode
[/HIDE]
nptv(n): Nptv command "not the foggiest idea of what these do."[HIDE]
[Help]
Ycproc(ycproc): YCPROC Command
TVD(tvd): TVD Command
NR(nr): NR Command
SCART(scart): SCART Command[/HIDE]
dbs: Dbs command "not this either"[HIDE]
[Help]
init(i): Dbs init
print(p): Dbs print at once
reset(r): Dbs reset[/HIDE]
dmx(d): Demux commands "This looks like the solution, except... the one command does nothing..."[HIDE]
[Help]
query(q):[/HIDE]
memtest: Memory test[HIDE][Help]
run(r): Memory test[/HIDE]
pdwnc(pdwnc): PDWNC commands "another one that just returns [Help]. no idea what it is"
bwt: BWT command "BandWidth Testing. not what I'm looking for I don't think"[HIDE]
[Help]
init: BandWidth Testing Preliminaries
testing: BandWidth Testing (BWT)
report: BandWidth Testing Report
chgchannel: Change Channel Number
dtv: BWT for DTV
atv: BWT for ATV
cvbs: BWT for CVBS
ypbpr: BWT for YPbPr
hdmi: BWT for HDMI
vga: BWT for VGA
src: Get current input source
mtime: Set BWT measure time
pippop: BWT for PIP/POP[/HIDE]
gpio: Gpio interface "General Purpose I/O. Don't think this is what I need either as it's hardware" [HIDE]
[Help]
output(out): gpio.out [gpio num] [[0|1]]
input(in): gpio.in [gpio num]
servo(servo): gpio.servo [0-4][/HIDE]