How to fix damaged flex cable?

Hi Mary Anne,

I'm afraid the flex cable can't be replaced; it is connected directly to the LCD and the digitizer glass, and those connections require extremely specialized equipment and expertise to bond them. The only real option here is to go ahead and replace the screen.

Sorry to say iFixit doesn't have a guide to that repair for your phone, but there are plenty of YouTube videos out there showing you how to accomplish that. Here's one that looks pretty good.

REALME C21Y LCD REPLACEMENT GUIDE - YouTube

I do have a couple of criticisms of this video, however. First, before you glue the screen back on, put it in place and connect it to the motherboard, then plug in the battery and verify that it works correctly. No reason it shouldn't, but if it doesn't you don't want to have to take it back off after it's been glued down.

Once you see it's all good, pop the battery back off and disconnect the screen and remove it.

Now for my second criticism, you'll want to clean all the old adhesive off the frame before gluing the replacement on. That'll make it as water resistant as possible and ensure the glue makes a good bond. I suggest 90% or higher concentration of isopropyl (rubbing) alcohol and some cotton swabs.

After that, you'll need either a sheet of precut adhesive or a tube of glue; look for something like B7000 to maybe T7000; you can get those on eBay, AliExpress or Amazon with no problem. Same goes for sourcing a screen; search online for a Realme C21Y screen replacement and you shouldn't have any trouble finding one.

Good luck, and be sure to come on back and let us know how it all turns out!