Dual HDD stops my Asus laptop from turning off

Hi, there

Recently I installed new SSD drive on my Asus x550ca laptop.

I put SSD into main slot in front and old HDD into DVD drive slot via dedicated HDD caddy

Everything works very well but somehow additional HDD stops computer from turning off.

Windows logs out, no signal from SSD, no signal to display but HDD is still going.

I've gone through few forums but found rather "extreme" advices of DIY modifications to motherboard and HDD caddy itself.

No ideas so far.