Mash Temperature/Conversion Flub

[drubes14]

Hoping for some input on what could be a disastrous beer.. Yesterday, I made an all grain oatmeal stout, with an expected OG of 1.053.

Naturally, I ran out of propane just as I was starting the mash, so I brought my brew kettle in to the electric stove. I was aiming to maintain a mash temp of 155.. anyway, electric coils be damned, i went to do a load of laundry and somehow the temp had soared from 145 to 170 in the 10 minutes i was away. i do BIAB, so I instinctually pulled out the grain bag and tried my best to pull the temp down with ice. the grain was exposed to upwards of 170 for probably 5 minutes, along with probably 10 minutes as the wort drained out of my grain bag. I ended up mashing the rest at 148, so as to to get some more simple, fermentable sugars to balance out the high temp flub.

measured OG was 1.048.. so, here's the question: with a 66% efficiency, what should i expect from the beer? something full bodied and cloyingly sweet from the extremely high mash temps? i was happy to see there was some conversion at all- i thought i would have knocked out the enzymes.

 

[drubes14]

To clarify, instead of wrapping my kettle in a blanket as most BIABers do, I just keep the stove on low.. it has worked numerous times for me in the past, and I have been very happy with the results. The 170 temp was not the strike temp, but the actual mash temp.