Lines on screen are common but often difficult. Sometimes fix is simple (loose ribbon cable), sometimes expensive (T-Con board or panel). Diagnosis determines this.
See if any of these signs match your device — each one increases the likelihood of this fault.
These are the causes we encounter while repairing Lines on screen — ranked from most to least common.
Loose ribbon cable between T-Con and LCD
Bad T-Con board (multiple horizontal lines)
Dead line in LCD panel itself (irreparable)
Damaged COF cable
Faulty driver IC at panel edge
Voltage spike burnt part of panel
Any of the following = a danger signal — call now and don't try to fix it yourself.
On-site diagnosis, clear pricing before any work, and a documented 6-month warranty.