That looks like some flux residue. Use some 90% or stronger isopropyl or denatured alcohol and a toothbrush/cloth to gently clean it up. It is hard to tell from the photo but some of those pins do not look well soldered to me.
Jeff From: M100 <[email protected]> On Behalf Of Gregory McGill Sent: Sunday, July 8, 2018 10:42 AM To: [email protected] Subject: Re: [M100] model 200 arrived.. https://photos.app.goo.gl/R7p1wJ7kvVEgmELMA some gunk by the corner there On Jul 8, 2018 6:35 AM, "Jeffrey Birt" <[email protected] <mailto:[email protected]> > wrote: The fact that the whole screen clears shows that the LCD is being reset, i.e. all LCD driver chips are getting reset and clearing each pixel, the default power on state of each pixel is black. So, this should mean that the LCD itself is OK, as it can go to both black and clear. A ‘RESET’ goes to each chip and this line is toggled as part of the start up sequence.
