Does the CARES act mean I don't need to take all of my RMD for 2020?

That is correct.  Under the Cares Act, the RMD requirements were waved for 2020.  You will need to delete your 1099R and re-enter it.   After you have logged in and are in your return in TurboTax Online:

 

• Go to Search at the top of the screen.
• then enter Form 1099-R in the search box. 
• You will see a Jump To function that will take you to the 1099-R input screens. 
• There delete the 1099R in question by clicking on the trash can next to the form
• Then add a new 1099R and manually enter your 1099R.

At the financial services screens, click "Change how I enter my form" then "Type it myself"

You must indicate to TurboTax that none of the distribution was RMD.  If you already enter the 1099-R as RMD and changing your answer to the RMD question doesn't work then you have to delete and re-enter the 1099-R form. 
  
You can verify your entry by looking at your Form 1040 line 4 or 5:

1. Click on "Tax Tools" in the left menu
2. Click "Tools"
3. Click "View Tax Summary" in the Tool Center window
4. Click on "Preview my 1040" on the left

 

The pandemic has affected your taxes in many ways. Including reporting in TurboTax the amount of stimulus money you received. Click Here for more information on how the Pandemic affected your 2020  taxes.

 

I took the RMD and subsequently returned it back to my IRA account.  I was told there would be no tax consequences and no tax form would be generated.  To my surprise, my managing brokerage house issued 1099R anyway.  The customer service says I must enter Form 5498 as a Rollover.  I am not so sure how it is done.  Do I enter 1099R as if I took the money and then enter 5498 for the same amount?  Please help.

Just enter the information from the 1099-R in TurboTax and in the screens that follow you can indicate that you returned the RMD.  Form 5498 is just for your information and isn't entered in your return.

 

To indicate that you returned your required minimum distribution (RMD) to your IRA, please follow these steps:

 

TurboTax Online

1. Click on Federal > Wages & Income.
2. Scroll down to the Retirement Plans and Social Security section and click on the Start/Revisit box next to IRA, 4701(k), Pension Plan Withdrawals (1099-R). 
3. If you've already entered one (or more) 1099-Rs, you will see a screen Your 1099-R Entries.  Click the Edit link next to the 1099-R you wish to review.   
4. On the screen, Tell us if you moved the money through a rollover or conversion, mark the radio button,  I rolled over some or all of it to an IRA... and click Continue.
5. A few screens after the 1099-R input screen, you should see a screen, What Did You Do With The Money From 401k institution?  Mark the radio button next to I moved the money to another retirement account (or returned it to the same retirement account).  
6. On the next screen, Did you rollover the gross amount of $XX (Box 1)...  mark the appropriate radio button and click Continue.

 

TurboTax CD/Download

1. Click Federal Taxes > Wages & Income > I'll choose what I work on
2. Scroll down to the Retirement Plans and Social Security section and click on the Start/Revisit box next to IRA, 4701(k), Pension Plan Withdrawals (1099-R). 
3. If you've already entered one (or more) 1099-Rs, you will see a screen Your 1099-R Entries.  Click on the Edit link next to the 1099-R you wish to review.   
4. A few screens after the 1099-R input screen, you should see a screen, What Did You Do With The Money From this Payer?
5. Mark the radio button next to moved the money to another retirement account (or returned it to the same retirement account.
6. In the next section, mark the radio button next to the appropriate  selection [moved it all or did a combination…]
7. If you selected combination, a box will appear to enter the amount you rolled over or converted.  Click Continue.
8. Continue through the rest of the interview.

@kck1