It may be need to be cleaned, it may need to be sealed to prevent leakage, it may need both.

From there we need put an ozone cleaner in the unit, Lysol the remaining drywall and surfaces, seal everything up with BinZ sealant and primer, and begin rehabbing the unit.  

This is the preparation and learning stages and I feel confident that I'll seal the deal before this year is up.T.C.

I can use my rubber mallet, the handle of my screwdriver, or in a pinch I've even been known to just stand on the paint can lid to get it to seal. 

(the box has 240V inside and doing anything with it is probably not safe for the average homeowner...meaning be safe and call an electrician---if you hit a live part inside the box it will send you 6 feet underground pretty quickly...have someone qualified look at it and repair it--there may be other (handyman type errors) problems inside it that need fixing like the open holes need fixing.)https://www.homedepot.com/p/Halex-1-2-in-Knock-Out-Seals-4-Pack-26071/100191724Good Luck!

The premix self seals in 24 hours and is easier to clean and repair.

Usually I get something like looks like this:Exterior Landscaping - $3,800*Trim trees*Trim bushes, remove vines and vegetation growing on home, and remove small trees growing around foundation*Remove trees growing through fence and around fence line*Install fill grade dirt around foundation and level yard*Install mulched flower beds*Slurry seal drivewayTypically, they are going to charge to give a quote for a breakdown like this unless you have an established relationship.

I would power wash then apply a seal coat. 

Mold was cleaned up, and HVAC replaced, but the problem wasn't really solved until I installed a dehumidifier and sealed the crawlspace.Good luck.

Issues with other tenants is notsomething you should resolvealthough the area where smoke is getting in should be sealed off.