I wish I had found this topic a long time ago.
Hinge issue (now both) on dm4-1050ea
An additional thing I noticed before hinges became detached from screen assembly/top cover was that they had become increasingly stiff; I daren't move the lid for fear of snapping the attachment - which is what did happen. So in my case I am of the opinion it wasn't the weak anchor that was the root cause, it was the hinges locking up. Of course, the screen became damaged down the left hand side for a bout a 1cm width strip but the screen is actually useable at a push, if it it is carefully supported. The anchor point on top cover may have failed in due course anyway, of course.
My (simple) solution to the issue, having had a difficult time even communicating the HP support group who were unable to help in the end, at any cost less than buying a new computer (HP seem really only interested in selling their latest and [not their most expensive tho'] expensive models) (I think this was early 2015 so well out of warranty), was to get a larger external screen 21.5" (about 60 GBP), wireless k/b and mouse (10 GBP) and and an HDMI cable (2 GBP), connect it up, and now I have a fixed computer and screen with a k/b & mouse that I can use from my armchair, with a nice big screen. The system isn't portable oof course, but I found a 2kg weight a bit awkward to carry about anyway.
I found a youtube video which involved the hole drilling, which it seems is the best way of solving this problem but I can't give ref. because my mmy HP with it has just failed. Sorry. My other dm4s are ok so far...but I've not used them much (all second hand)
Woodwood
9.March.2017