A 2,7 code relates to Display Failure. You may need to replace the display but you can also open up your laptop and check that the display cables are seated properly and not damaged/crimped.

Unfortunately if the board doesn't detect a display then you won't be able to plug in an external display to get it to work. It's worth a try though.

It seldom works but you can also try a power drain to reset the system.

Unplug the power adapter and the battery. Hold the power button down for 30-60 seconds. Plug the adapter back in and test. You will have to open up your laptop to unplug the battery from the motherboard. 

is there any way and is this bios chip problem?

i tried to connect on another monitor and its not working still is same beep

i opened last week and mabe display cable was good condition so what can i do? whene i'm pressing D for display test its still black screen

https://www.dell.com/support/manuals/en-us/alienware-15-r4/alienware-15-r4-service-manual/diagnostics?guid=guid-5c341b78-b63d-499c-89d4-d341c006e437&lang=en-us

Don't think it will be a BIOS issue. Check the display cable connections first and go from there

thanks u but look, Craftsman checked the laptop and he told bios chip problem. i dont remembered exacly but he told this machine has 3 bios chip and one of them is cleared and he dont have a licence to flash the bios . in my country Craftsmans are dums so is there any chance and its bios chip problem?

I found a guy on Reddit with an answer.

I have never had this problem, but I have taken apart my 15 R4 quite a few times to fix thermal issues.

"LCD failure" is not very specific. It could simply be that the LCD connection is loose.

I guess the best-case scenario is that it's just the connection to the LCD. It's possible the LCD connector on the north side of the board became a bit loose when you took out the battery. So the first thing to try would be to pull it out and try to plug it in again and make sure it's seated properly. Also check for any dust or corrosion on the connector and clean it with a bit of rubbing alcohol.

You don't need to take the whole system apart to get at the LCD connector. You just need to take off the bottom outside panel and the black plastic IO shield. You can then turn the laptop rightside up and you will see the LCD connector and 2 other connections at the back.

If it's not the connector, then it could be the LCD circuit on the MOBO, or the LCD panel itself. This would mean that 1) running without the battery caused a short because the design of the charging circuit sucks OR 2) pulling out the battery connector physically damaged some component on the board, even though you were careful. This can happen if there's a component that's about to fail or the solder is cracked.

Either way, if cleaning and replugging the LCD connector doesn't work, you would need to send your system to Dell or buy the parts to attempt to fix it yourself. Fixing it yourself is a bit risky because you don't know what component failed exactly. You could end up buying a new LCD panel and connector for around $200, go through the process of installing it, and then find it was actually the MOBO that failed.

All signs point to a display failure or bad cable connection. You can try to do a BIOS recovery using the guide below. At this stage it's worth trying anything.

<ADMIN NOTE: Broken link has been removed from this post by Dell>

You should also have some very small CMOS jumper pads on your board (possible near the RAM slots). I don't have your laptop but it may also be worth trying to reset the CMOS (BIOS) by jumping these pads. 

Have a look through the Service Manual to see if there are any troubleshooting tips that could help you.

https://topics-cdn.dell.com/pdf/alienware-15-r4_service-manual_en-us.pdf

I dont even understand how a bios chip is going to cause a display not to turn on.