Data Recovery after Bootloop? Please advise.

So day before yesterday my dads phone asus zenfone 2 (Z00AD) went into bootloop. it kept booting repeatedly never making it to the home screen. anyway, he took it to asus repair and we got the phone back today. its back to normal but all data is lost. (We had not backed up anything) I downloaded a few android data recovery softwares like mobikin and dr fone but they require the android to be rooted to scan for lost data.

Now my question is, do you think its possible to recover data once the phone has been flashed? I am apprehensive to do the rooting and will only go ahead with it if there is a real chance some lost data may be recovered through such android data recovery softwares.

Please advise. Should I go ahead and root and give it a try?

thank you so much in advance.

Need quick advise for a new phone.

Had my ATT SGS5 swiped on Monday night and need to get a new phone asap, so here's my question - given how Samsung started locking bootloaders and doing other nonsense here in US, what would you guys recommend I get, from B&H or another online store.
Criteria would be for it to have lots of development/root, SD slot, and be waterproof similar to how S5 was. Would prefer physical key(s)/scroll pad and VERY good battery life. Budget I would say the lower the better, seeing how S5 goes for ~0 used, but I'm willing to go up the price ladder for worthy features.