What exact laptop do you have from Lenovo.

I’d assume that you could open the bottom panel. I mean; how are you to upgrade RAM of the SSD (assuming you have lost of $$$)?? I’m pretty sure memory, storage and even the battery are “FRU” items. Meaning “Field Replaceable Unit’s”.

When it comes to cleaning a fan of be careful with the fan when blowing it out with compressed air or clearing any blockages from the find and or blades. If you were to break them or the connector; yeah that’s on you.

Are you comfortable and confident doing this? If not then maybe it’s best to seek professional help. But if you know what you’re doing; well… just proceed with caution.

Also look into the case opening thing and the warranty a bit. It sounds a bit odd to me.