Uniden remote control/programming commands which work also on the UBC-3500XLT.

Jump to mode:
JMP, mode
mode = CC_MODE, SCN_MODE, FTO_MODE, CTM_MODE, SVC_MODE

Menu mode:
MNU, menu_index
menu_index = SVC_MENU, WX_MENU, CCBAND_MENU, SCR_OPT_MENU, GL_LIST_MENU, SETTING_MENU

Scanner option settings, works only in programming mode (PRG, SCN, EPG):
SCN

Simple Python code for finding Uniden control/programming commands which response is something else than b'ERR\r'

import serial

ser = serial.Serial('COM3', '115200', timeout=2)
print(ser.name)
#ser.write(b'PRG\r')
#s = ser.read(32)
#print(s)
i = 65
j = 91
cnt = 0
print("start")
try:
    for x in range(i, j):
        for y in range(i, j):
            for z in range(i, j):
                k = chr(x) + chr(y) + chr(z) + '\r'
                if ((k.find("PRG") == -1) and (k.find("EPG") == -1)):
                    ser.write(bytes(k, encoding='ascii'))
                    s = ser.read(16)
                    if (str(s).find("ERR") == -1):
                        print(s)
                    cnt = cnt + 1
                    if (cnt % 32) == 0:
                        print(cnt)
except KeyboardInterrupt:
    print("KeyboardInterrupt")
#ser.write(b'EPG\r')
ser.close()
print("end")

ser.read(16), probably better use e.g. ser.read(256), some commands return quite big response (e.g. LCD content).

POF is power off, to skip it, modify:
if ((k.find("PRG") == -1) and (k.find("EPG") == -1)): =>
if ((k.find("PRG") == -1) and (k.find("EPG") == -1) and (k.find("POF") == -1)):