Hello my name is Eric,
Welcome to Just Answer
I can help you with this issue,
The solution may be simple
3 blinks is the error code for the lamp door switch not being closed tightly.
I suggest removing the lamp door , making sure the lamp is all the way in secure and straight . Look closely at the lamp door for the tab that sticks out and contacts the little switch lever in the hole.
Reattach the lamp door and make sure it is secure.
If the switch was damaged during the lamp install you will need more tech help
I hope its just loose
If you need more help please tell me
What number best describes you
1. I just want to know what to expect a repairman to charge me,
2.I want to try pushing buttons and checking connections
3. I will open the TV if needed, but have limited tools and skills
4. I have technical skills and have a soldering iron and or voltmeter
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As always, POSITIVE FEEDBACK and BONUS are always appreciated.
If you have more questions you can still respond until this post expires,
I will reply asap