Thanks for your replies.
This is in Austin,TX region where I am told putting 2% as Earnest money (400K * 2% = $8K) is quite common to show the buyer is serious... and also Inspection-waiver clause is something that I have known few friends have done to win an offer.
With the several hail storms over the years in that region,
@Theresa Harris, @Jaron Walling There are no current leaks, but 3 separate roof contractors have suggested to replace the roof immediately (all of them could be biased)... Also, I am afraid that the insurance would be rejected once they inspect within a 30-60 days of insurance coverage start. In case you are interested, these are the pics of the roof: Roof-Pics.
@Dan Maciejewski when you say, "file suit to make them settle" -> Can I pursue that even after purchasing the house. I do plan to go ahead with the purchase even if I have to pay it out of my pocket... The seller (opendoor) does realize this, but I made it clear to the seller that I am approaching an attorney.
To be explicit, I am content if we settle on a middle ground, say $4k - $5k credit. Is there an option of "small courts" settlement without going through an Attorney and the appropriate fees?