First off I'm a total noob of average intelligence so assume you are talking to a five year old.
I have an ATMEGA 328p soldered onto a prototyping board (16k oscillator version) along with an rtc module. I also have two pins hooked into a relay. The grounds and power pins are all attached to bars on each end of the board. It is all powered by a 110 to 5vdc module here - (https://www.amazon.com/gp/produc...). Most of the components are sweatshop material Arduino knockoffs. The thing is supposed to run a water pump and heat lamp for a terrarium. My problem is when I hook up the power rail and ground rail to the power module the code goes off the rails and nothing works right. I can hook a UNO board to the RX and TX pin and in the serial monitor what is supposed to be displayed is just jumbled robot code (not sure what its called). The strange thing is when I disconnect the power module and just pin the power/ground rails to the 5v and gnd pins on the UNO board everything works perfectly. I added two 100nf caps between the 328 gnd and vcc pins on the bottom of the prototype board, not sure if done right but it didn't change anything. If I connect the reset pin to the 328 reset it makes the serial monitor show a little of the code it is supposed to but it is still mixed with the enigmatic robo code. It also won't upload code through the RX and TX pins on the power module power but works flawlessly when powered through the UNO pins. I have some pictures that may help.
Thanks for your time.