Never messed with one of those, but at a glance on google it mentioned turning the n64 on with a cartridge in the 64 slot then once it boots remove it and place it in the CD64 slot. If you was able to accomplish this once after cleaning, you might try cleaning it again and check all the connections. Good luck with it.
...also welcome.
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Wisdom comes from experience. Experience is often a result of lack of wisdom.