IMac A1213 Core i5 severeal Problems

[LuiJP]

Thanks!
a friend gave an imac A1312 Ci5, he has, I believe, several problems:
1-when I turn it on, sometimes the normal login screen appears, asking for username and password.
2-As I don't have the data, I try to enter recovery mode.
3-I restart the imac and only a white screen appears, sometimes it enters the internet recovery mode, turning the earth logo, when it finishes, the screen blinks and goes blank.
4-Restart again, sometimes the screen appears white and then it goes all black.
5-I changed HDD, tried to install the OS again, sometimes it recognizes the USB drive and sometimes not, sometimes it recognizes the key combination to enter the different modes and sometimes it doesn't detect anything and just stays on the white screen.
6-Already change the RAM memories, deep cleaning, new thermal paste, and nothing.
I have done everything, I believe, I humbly ask this forum to help me please.
Thank you very much.

 

[TonyAguila]

Thanks!
a friend gave an imac A1312 Ci5, he has, I believe, several problems:
1-when I turn it on, sometimes the normal login screen appears, asking for username and password.
2-As I don't have the data, I try to enter recovery mode.
3-I restart the imac and only a white screen appears, sometimes it enters the internet recovery mode, turning the earth logo, when it finishes, the screen blinks and goes blank.
4-Restart again, sometimes the screen appears white and then it goes all black.
5-I changed HDD, tried to install the OS again, sometimes it recognizes the USB drive and sometimes not, sometimes it recognizes the key combination to enter the different modes and sometimes it doesn't detect anything and just stays on the white screen.
6-Already change the RAM memories, deep cleaning, new thermal paste, and nothing.
I have done everything, I believe, I humbly ask this forum to help me please.
Thank you very much.

How about hardware test? Start up while holding down the “D” key. If you are using a bluetooth keyboard, you may have to connect it with the charging cable.

 

[LuiJP]

Thanks for the answer. I connected the keyboard via USB and it does not start recovery mode. As it says before, sometimes enter to choose the start unit, after that, only the white screen remains, other times, the screen is black. As a comment, when I received it from a friend, it started, but stopped at the Username and password, so I changed the HDD drive for an SSD that had Windows 10 installed. Then it started normally and loaded the system, more, when it was about 15 or 20 minutes working, the machine restarted. Then I put more RAM and that's when he started having problems. Any suggestion?

 

[Jonah]

Sounds as though you need to return the system to its original RAM and carry out the Hardware Test again.
Might be being compromised by the new RAM

 

[LuiJP]

Thanks for the help, I'll do that right away and then write the answer.

 

[LuiJP]

I re-installed the original memory, as well as tried re-installing the OS using flash drive. Sometimes, it turns on the white screen, then everything is black, others, it enters the install mode, the installation bar appears and when it ends, it stays on the "famous" white screen and then it doesn't come out. I'm about to give up.