DELL G3 Boot Problem

Please help me. I have a serious problem with my new Dell Laptop right now. Below is the story of my problem chronologically:

1. I bought a Dell Inspiron Gaming G3 579 i5 8300H/8GB/1TB+16GB OPTANE/GTX1050 4GB via online shop on 19 March 2019. The laptop arrived on 20 March 2019. The laptop was equipped with 1TB (5400 RPM) HDD, 16 GB Intel Optane, and 8 GB DDR4 RAM (2 x 4 GB). There was no problem at all with the laptop at first running. All condition is good.

2. Before I bought the laptop, I had a plan to upgrade the laptop with "256 GB SSD" and "8 GB RAM". On 21 March 2019, I bought "256 GB SSD M.2 PCIe NVMe 1.3 Gen3x4" and "SODIM 8GB DDR4 PC2400 RAM " via online shop. The stuffs arrived on 22 March 2019.

3. On 22 March 2019 evening, after I went home from work, I started the process of upgrading my laptop. First, I backed up the windows system into a flashdisk using the "Dell OS Recovery Tool". Next, I upgraded the RAM. The new RAM was succesfully installed and the Windows system recognized the new RAM properly. I was also able to log into the Windows system after the RAM upgrade. So now my laptop has a total of 12 GB RAM (1 x 4GB + 1 x 8GB) installed.

4. After upgrading the RAM, I installed the SSD by removing the Intel Optane and attaching the SSD into the Intel Optane slot, but without disabling the Intel Optane first. Problem arose after the SSD installation: I could not log into the Windows system. To fix this, I installed the Intel Optane back again, logged in into the Windows, disabled the Intel Optane and then repeating the same process of installing the SSD as before. This time, it worked. I was able to log into the windows system again and the SSD was successfully recognized as a new storage (even though after that the windows booting-speed was decreased very significantly).

5. Because I wanted to use the SSD as my primary hard disk, I cloned the Windows OS inside the hdd to the SSD using "Easus to do Backup" software. But unfortunatelly it didn't work. The cloning process was stopped in middle of the process. Then I switched to "Macrium Reflect" software to clone the OS. And it worked, the OS was now successfully cloned into the SSD.

6. The remaining process that I believed need to be done at that time was to set the boot sequence priority in BIOS to SSD. But when I entered the BIOS, I couldn't find any options there to change the booting priority. Not giving up, I tried to change some other bios configuration options (options that I thought related to the booting configuration), but it didn't work: the booting priority still set to "Windows Booting Manager".

7. Having tired of trying and being afraid of having future problems due to the change in BIOS configuration settings, I felt tempted to click on the button on the bottom-right corner of the bios screen that says: "Restore Setting". After I clicked on the button, a dialog then popped up that prompted me to select one of two options: "Factory default" and "Bios default" (I don't remember the words in details). I finally chose the "Bios default"!.. without any sufficient understanding on the true meaning of the options being presented.. And what I feared most came after that: The computer failed to reboot... It kept trying, but failed.. I have already tried a ton of suggestions to troubleshoot the problems but to no avail.. The computer have never been able to boot successfully again since then..

8. This is the situation i encounter now when i try to turn on the laptop: When i click the power button, the laptop and the keyboard back-light get turned on, but then the laptop get automatically turned off after a few seconds, even before the Dell logo appears on the monitor. A few moments after that, the laptop tries to get back turned on again automatically, and then get turned off again almost immediately, and apparently this things will happen repeatedly forever if i don't manually turned off the laptop by long-pressing the power button. I have tried to remove the hard drive and RAM, put the intel optane back to its slot, and removing the coin-cell battery after that, but still that didn't solve the problem.

Please help me... Do you have any suggestions on what i should do to fix this problem?