Magento 2 – How to Update Block Programmatically?

Use this

Load by block id:

Mage::getModel('cms/block')->load($id)
  ->setData('content', 'SET CONTENT HERE')
  ->save();

Load By identifier:

Mage::getModel('cms/block')
  ->getCollection()
  ->addFieldToFilter('identifier', 'block_identifier')
  ->load()
  ->setData('content', 'Example content')
  ->save();

Here is an example how to insert cms data in m2

Here is an example how to update cms data in m2

Now you can try following way for insert cms data:

public function __construct(
    \Magento\Cms\Model\PageFactory $pageFactory
) {
    $this->pageFactory = $pageFactory;
}

And now:

$cmsPage = [
    'title' => 'TEST TITLE',
    'identifier' => 'test-content-1',
    'page_layout' => '1column',
    'content' => 'test content 1',
    'is_active' => 1,
    'store_id' => [0],
    'sort_order' => 22
];
$this->pageFactory->create()->setData($cmsPage)->save();
$setup->endSetup();

For Update:

$newPageContent = 'NEW PAGE CONTENT';
$newPage = $this->pageFactory->create()->load(
    'test-content-1',
    'identifier'
);
if ($newPage->getId()) {
    $newPage->setContent($newPageContent);
    $newPage->save();
}