Default Smashed Screen - Need Repair Advice

Hey all

I recently got a dirt cheap HTC One off eBay but it has a few problems. The previous owner dropped the phone (which smashed the screen) and after a few months the phone wouldnt turn on but the thing is the phone can still connect to PC if a USB is connected to it.

Before opening the phone which i have read to be a impossible headache online i would like to get some expert advice from people who have had experience
1) For anyone who has opened the HTC One before do you recommend it, if i use a hairdryer and heat up the back cover before trying the back off with a suction cup
2) Do you guys thing the problem is as simple as replacing the LCD and the digitizer assembly

Thanks for your help