Chosen Solution

My MacBook Pro 17" mid-2009 monitor remains black. I’ve already tried all the possible resets I found on web discussions (SMC, PRAM, hold power, …). Now I’m using it with a VGA monitor through mini-display port. I’ve launched the Apple Test Hardware, which for models before 2013 has to be done via USB, and it has found this error: 4SNS/1/40000001: TB1T-0.000 This code refers to a temperature sensor error, according to this page. The internal battery was the original one and it was to be replaced for a long time. In fact, my MBP was unusable without straight power. The monitor went black probably because of drops of rain during a show. After few tries to restore it, I touched the bottom case, where the battery resides, and it was really hot. I had to wait for the end of the show (3 hours late) before physically remove the battery. When I removed the back lid, the MBP’s fans were still running. Apple does not give furthermore any technical support for my model. Is there any change to fix the problem by myself? (I’m pretty technically skilled) Is it possible to find the hardware component that has to be replaced? At least, what any possible solution you suggest to carry on using my MBP? (it has lots of software which I was for work).

MacBook Pro 17" mid-2009 OSX 10.11.6 2,8 GHz Intel Core 2 Duo 8 GB DDR3 @ 1067 MHz NVIDIA GeForce 9400M 256 MB SSD (OSX) Samsung SSD 850 EVO 250GB HD (internal backup) Seagate ST2000LX001 2TB SATA Hard Drive —- 01 Aug 2018 The problem was the backlight. I brought it to a skilled technician who have cleaned the LVDS connector from melded plastic and oxidation caused by water using a microscope. Now it works perfectly. Thanks to Arbaman for this suggestion: “Try reseating the LVDS cable after cleaning and checking there are no signs of burns or oxydation. Shine a light to the screen to check if you can see a faint image to determine if it’s lack of image or lack of backlight.”

It seems you got different issues not necessarily connected with each other. Sensor error seems to be battery related and it would be coherent with battery age and overheating. Trying a replacement battery would be a must in this case in my opinion. Since the Mac got some drops of water it might be they ended in the wrong place, inside the screen or somewhere along the cable. Try reseating the LVDS cable after cleaning and checking there are no signs of burns or oxydation. Shine a light to the screen to check if you can see a faint image to determine if it’s lack of image or lack of backlight. In either case though, buying parts for testing, looking for schematics and boardview and troubleshooting a backlight driver or image data lines needs time, money and efforts. Although Apple doesn’t service such older Macs, there are some labs specialized in Apple repairs that might be able to help.

There are quite a few sensors within your system. The error is indeed a temp sensor failure within the battery (TB0T, TB1T, or TB2T). As for your screen: Are you able to see a faint image of your desktop & icons using a flashlight shining in through the Apple Logo in the lid (a poor mans backlight). If you are then the issue is within the backlight logic. Inspect the LVDS connector on the logic board for any corrosion pop off the bottom cover, disconnect the battery and carefully disconnect the large cable near the hinge in the corner. Take some pictures and post them here for us to see. Adding images to an existing question