These updates modernized the property, improved its curb appeal, and significantly increased its market value.

Money is getting tight, thinking about getting a personal loan to buy me some time. 

Let's say my 1st mortgage balance is $600k and I want to take out a 2nd mortgage for $150k for home improvements which makes the interest on the 2nd deductible as well.

There is rules around this which is why loans and utilities all offer multiple payment options.

I have a hard money loan on this place and it is maturing soon.My partner and I can keep lowering the price but we are already set to lose a Lot of money on it.

If you are investing for cash flow long term, you would benefit from paying off the loan sooner (eliminating interest). 

FHA loan How did you add value to the deal?

I wanted to find a property to improve that had a good foundation and structure, but needed a lot of cosmetic work.How did you find this deal and how did you negotiate it?

A lender usually a DSCR loan from a hard money lender.

I've also considered asking if the owner is interested in an assignable contract, I see hige value add here from the deferred maintenance that I personally can handle and coordinate to small improvements and raising rents slightly.