I decided to buy a Sega Genesis and a bunch of games and nearly all (9 out of 10) of the games I have won't work until I reboot the console numerous times. It displays the "Produced by or under license from Sega Enterprises LTD" message but won't go further unless I reboot the console multiple times. I don't have another Genesis console to try them out. Does this sound like a cartridge issue or a console issue?
Update: cleaning the carts didn't do anything
Clean the cart pins with isopropyl alcohol.
Tried that, no luck.
Keep doing it
Have you cleaned the cartridge slot?
Check the catridge slot.
If it’s not the cartridge slot it may be the capacitors. How are you with a soldering iron? Also what model of Genesis is it? You may need to recap the board. Console5 sells kits with the proper capacitors for your particular model.
Have you cleaned either yet?
Clean the cartridge pins
Spray Deoxit on both sides of a game's edge connector. Insert and remove it several times. See if your games work any better.
Try cleaning with electrical cleaning spray or you can use alcohol....clean the game cartridges as well with q tips and alcohol
if the connector pins don’t have any physical damage, try reflowing the solder on the circuit board where they’re plugged into the board. might have a cracked joint there.
Take a credit card, wrap it in cloth, dip it in isopropyl alcohol and clean the cartridge slot. If it won't help. next thing would be to resolder cartridge slot solder joints, or at leats check them visually, it may seem fine thou, but cracks might be there anyway
Also traces that come from cartridge connector might be corroded as well and needs to be soldered, you can disassemble cartridge that doesn't work and check it on the inside