I hibernated my Inspiron and now it does not power back on

Disconnect both the primary and CMOS batteries, hold the power button for 1 minute, and try again. However, turn the laptop on before reinstalling either battery; that sometimes helps. If the CMOS battery is dead, it's easy to tell because it will boot normally and reset the BIOS to default settings.

This is a known issue on many 7th—and 8th-gen Dell laptops—they are sensitive to having a good CMOS battery or will not boot. I suspect the CMOS RAM gets messed up when the battery is low, until it is reset back to defaults by disconnecting and reconnecting it, and the problem is permanently fixed by replacing it. Dell has had issues on a few laptops like this since the E7440.

However, disconnecting and reconnecting it (as well as the primary battery. Disconnect both to properly drain the CMOS RAM so it HAS TO go back to good defaults), which often acts as an immediate fix. I've even seen 7490s sold "as-is" due to this issue, so I once scored a $150 7490 with the 8350U/FHD LG IPS LCD :-). Mine isn't the top spec edition (that's a 4K IPS Touch/i7-8650U/32GB RAM/biggest SSD available from Dell out of the box. You rarely see these, but they exist). That said, I came from a bum with a dirty past (active lease where the machine was suspect, liquid damaged. I took what I could at that time.

Yes, I have seen 768p BOE TN ones (I have one as a throwaway with the 8250U) machines, but most have the LG IPS LCD or the BOE IPS LCD. The best units come with the LG part.

The permanent fix to this problem is a new CMOS battery, especially if it tests at 2.5V or lower, or is borderline (use a cheap multimeter; even a cheapo one from Walmart will work to check these batteries as they're low voltage). Follow this guide to open the laptop to reseat/replace the CMOS battery. On yours, if it's dead, you can use any off-the-shelf battery that is socketed and not one of the Dells with the wiring harness. Even then, the battery known to cause issues is so cheap it wouldn't hurt to change it to mitigate the issue completely. I consider it a consumable item like the primary battery once the computers known to have this problem enter the hands of DIYers at Walmart special prices, especially once the R2 facilities begin selling them off without SSDs.