PRESS TAB to turn on the TV.
Or press Enter tap the menu button at the bottom of your touchscreen, and then choose the 'Turn on TV' option.
Edit: This fixes the pit bug! Enjoy 5 lives in your quest to take down... well, you know... :p
(old version with bottomless pit death hanging bug removed)
Update: 1222017 - New version that fixes some bugs, makes the boss affected by fireballs, boss flashes on hit and has an HP counter so it's easier to see if you're hurting him... And all 4 levels are more unique now.
...Ohhhh and I heard a rumor that if you clear the game at least once and collect 300 coins (cumulative across all play, even between shutdowns)... something interesting could happen the next time you reload this cart. I think it's probably just a rumor though. I mean.. who would believe something like that?
Old, buggier version: