Hi,
As a DIY repair all you can do is to open the tablet and check if the LCD display flex cable connection is secure to the systemboard and if so, then to temporarily replace the display module and check if it now works OK.
Here’s the ifixit Lenovo Yoga Tab 3 8 LCD Replacement guide which will help to do this.
Here is a link that will get you the correct replacement part for your particular model variant. Type YT3 850F (if this is part of your model number) in the search box and then select which model variant is yours i.e. ZA09, ZA0A or ZA0B.
Then click on Select Commodity > Covers all second LCD & LED Displays to find the part number for the display assembly. Then search online using the part number only to get suppliers that suit you. The part number is usually also printed on the back of the LCD display somewhere if you wish to verify that you have the correct one.
It appears that the same displays are used in all 3 variants, except the -0A version which has only the one option (part #5D68C02838), whereas the others have two to choose from, (part #5D68C02838 & #5D68C07614)