so for cheat 6 i couldn't get it to work except for slot 3. which is fine since all the upgrades before that cost about $30k total.
for cheat 7 i got all of them to work.
just keep spamming the button and checking the upgrades till they work.
hope that helps a bit.
Yeah I have to say option 6 only opens slot 3.
Also option 7 I had to spam the key a lot to get it to work.