How do I clean gel residue inside the nail lamp?

First, turn off and allow the lamp to cool down. Then, use a cotton pad soaked with 75% alcohol to wipe the gel residue. If the gel has hardened, you can soften it first and then gently scrape it off.
Avoid using nail polish remover or strong, corrosive cleaners (like acetone or gel remover) as they may damage the machine. If your lamp has a removable base, it's also recommended to clean it regularly.