5 beeps would be a CMOS battery (coin cell) issue. Try replacing the battery per the following service manual instruction.

https://downloads.dell.com/manuals/all-products/esuprt_laptop/esuprt_inspiron_laptop/inspiron-15r-5521_owner%27s%20manual_en-us.pdf

Also this video will help. Go to about 1:21 on the video and you will see the CMOS battery on the right side of the screen. Pop it out and replace it, a CR2032 battery and very easy to find and inexpensive.

https://www.youtube.com/watch?v=ufjcMjMLmTk

EDIT:I must be getting old..and typing much slower than Mary G..also thinking much slower..  :Embarrassed:

That's a real time clock failure. Replace the cmos coin cell battery. Check the manual for directions. The battery can be purchased at any store for about $2 if it is the standard CR2032 battery.

Note that replacing the battery is a complicated procedure. You have to take the laptop apart. Take pictures if you do it yourself. It could also be a motherboard failure so be prepared to buy a new laptop.