TransBot

Move underground:
Destroy the Arm Carrier and capture the Arm Capsule, which resembles a bubble marked with a question mark. Seven letters will begin to flash in order on the top of the screen. Press 1 when "D" is highlighted. Wait until Hilun flies towards your character, which resembles a blue diamond. Destroy them to allow your character to move underground.

Bonus Options:
Power on the Master System while holding button 2 on controller 1,
Continue holding the button (for about 10 seconds) until the options
screen appears the four options available are:

Option 1 = Start with 10 Lives.
Option 2 = Unlimited Arm Power (Except when you die).
Option 3 = Unlimited Power (Can't Die)
Option 4 = Slow down the weapon select cycle speed.

U = Option 1 ON / U+1 = Option 1 OFF
D = Option 2 ON / D+1 = Option 2 OFF
L = Option 3 ON / L+1 = Option 3 OFF
R = Option 4 ON / R+1 = Option 4 OFF
Press 2 on Controller 2 to exit the Menu